// Copyright (c) 2026 Lark Technologies Pte. Ltd.
// SPDX-License-Identifier: MIT

package mail

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"strings"

	"github.com/larksuite/cli/internal/output"
	"github.com/larksuite/cli/shortcuts/common"
	draftpkg "github.com/larksuite/cli/shortcuts/mail/draft"
	"github.com/larksuite/cli/shortcuts/mail/ics"
)

// MailDraftEdit is the `+draft-edit` shortcut: update an existing draft
// without sending it. Performs MIME-safe read/patch/write so unchanged
// structure, attachments, and headers are preserved where possible.
var MailDraftEdit = common.Shortcut{
	Service:     "mail",
	Command:     "+draft-edit",
	Description: "Use when updating an existing mail draft without sending it. Prefer this shortcut over calling raw drafts.get or drafts.update directly, because it performs draft-safe MIME read/patch/write editing while preserving unchanged structure, attachments, and headers where possible.",
	Risk:        "write",
	Scopes:      []string{"mail:user_mailbox.message:modify", "mail:user_mailbox.message:readonly", "mail:user_mailbox:readonly"},
	AuthTypes:   []string{"user"},
	HasFormat:   true,
	Flags: []common.Flag{
		{Name: "from", Default: "me", Desc: "Mailbox email address containing the draft (default: me). Prefer --mailbox for clarity; --from is kept for backward compatibility."},
		{Name: "mailbox", Desc: "Mailbox email address that owns the draft (default: falls back to --from, then me). Takes priority over --from when both are set."},
		{Name: "draft-id", Desc: "Target draft ID. Required for real edits. It can be omitted only when using the --print-patch-template flag by itself."},
		{Name: "set-subject", Desc: "Replace the subject with this final value. Use this for full subject replacement, not for appending a fragment to the existing subject."},
		{Name: "set-to", Desc: "Replace the entire To recipient list with the addresses provided here. Separate multiple addresses with commas. Display-name format is supported."},
		{Name: "set-cc", Desc: "Replace the entire Cc recipient list with the addresses provided here. Separate multiple addresses with commas. Display-name format is supported."},
		{Name: "set-bcc", Desc: "Replace the entire Bcc recipient list with the addresses provided here. Separate multiple addresses with commas. Display-name format is supported."},
		{Name: "body", Desc: "Full email body for a complete replacement (set_body). Prefer HTML for rich formatting (bold, lists, links); plain text is also supported. Body type is auto-detected. Use --patch-file with set_reply_body when you need to preserve an existing reply/forward quote block; use --body when you want a full body replacement. Mutually exclusive with --body-file. Cannot be combined with --patch-file body ops."},
		bodyFileFlag,
		{Name: "patch-file", Desc: "Advanced edit entry point for body edits, incremental recipient changes, header edits, attachment changes, or inline-image changes. Use --body/--body-file for quick full-body replacement; use --patch-file with set_body/set_reply_body when you need typed body ops, especially set_reply_body to preserve an existing reply/forward quote block. Run --inspect first to check has_quoted_content, then --print-patch-template for the JSON structure. Relative path only."},
		{Name: "print-patch-template", Type: "bool", Desc: "Print the JSON template and supported operations for the --patch-file flag. Recommended first step before generating a patch file. No draft read or write is performed."},
		{Name: "set-priority", Desc: "Set email priority: high, normal, low. Setting 'normal' removes any existing priority header."},
		{Name: "set-event-summary", Desc: "Set calendar event title. Must be used together with --set-event-start and --set-event-end."},
		{Name: "set-event-start", Desc: "Set calendar event start time (ISO 8601)."},
		{Name: "set-event-end", Desc: "Set calendar event end time (ISO 8601)."},
		{Name: "set-event-location", Desc: "Set calendar event location."},
		{Name: "remove-event", Type: "bool", Desc: "Remove the calendar event from the draft."},
		{Name: "inspect", Type: "bool", Desc: "Inspect the draft without modifying it. Returns the draft projection including subject, recipients, body summary, has_quoted_content (whether the draft contains a reply/forward quote block), attachments_summary (with part_id and cid for each attachment), and inline_summary. Run this BEFORE editing body to check has_quoted_content: if true, use set_reply_body in --patch-file to preserve the quote; if false, use set_body."},
		{Name: "request-receipt", Type: "bool", Desc: "Request a read receipt (Message Disposition Notification, RFC 3798) addressed to the draft's sender. Recipient mail clients may prompt the user, send automatically, or silently ignore — delivery of a receipt is not guaranteed. Adds the Disposition-Notification-To header; existing value is overwritten."},
		showLintDetailsFlag,
	},
	DryRun: func(ctx context.Context, runtime *common.RuntimeContext) *common.DryRunAPI {
		if runtime.Bool("print-patch-template") {
			return common.NewDryRunAPI().
				Set("mode", "print-patch-template").
				Set("template", buildDraftEditPatchTemplate())
		}
		draftID := runtime.Str("draft-id")
		if draftID == "" {
			return common.NewDryRunAPI().Set("error", "--draft-id is required for real draft edits; only --print-patch-template can be used without a draft id")
		}
		mailboxID := resolveComposeMailboxID(runtime)
		if runtime.Bool("inspect") {
			return common.NewDryRunAPI().
				Desc("Inspect a draft without modifying it: fetch the raw EML, parse it into MIME structure, and return the projection (subject, recipients, body, attachments_summary, inline_summary). No write is performed.").
				GET(mailboxPath(mailboxID, "drafts", draftID)).
				Params(map[string]interface{}{"format": "raw"})
		}
		patch, err := buildDraftEditPatch(runtime)
		if err != nil {
			return common.NewDryRunAPI().Set("error", err.Error())
		}
		return common.NewDryRunAPI().
			Desc("Edit an existing draft without sending it: first call drafts.get(format=raw) to fetch the current EML, parse it into MIME structure, apply either direct flags or the typed patch from patch-file, re-serialize the updated draft, and then call drafts.update. This is a minimal-edit pipeline rather than a full rebuild, so unchanged headers, attachments, and MIME subtrees are preserved where possible. Quick full-body replacement can use --body/--body-file; advanced body edits can use --patch-file with set_body or set_reply_body ops. It also has no optimistic locking, so concurrent edits to the same draft are last-write-wins.").
			GET(mailboxPath(mailboxID, "drafts", draftID)).
			Params(map[string]interface{}{"format": "raw"}).
			PUT(mailboxPath(mailboxID, "drafts", draftID)).
			Body(map[string]interface{}{
				"raw":     "<base64url-EML>",
				"_patch":  patch.Summary(),
				"_notice": "This edit flow has no optimistic locking. If the same draft is changed concurrently, the last writer wins.",
			})
	},
	Execute: func(ctx context.Context, runtime *common.RuntimeContext) error {
		if runtime.Bool("print-patch-template") {
			runtime.Out(buildDraftEditPatchTemplate(), nil)
			return nil
		}
		draftID := runtime.Str("draft-id")
		if draftID == "" {
			return output.ErrValidation("--draft-id is required for real draft edits; if you only need a patch template, run with --print-patch-template")
		}
		mailboxID := resolveComposeMailboxID(runtime)
		if runtime.Bool("inspect") {
			return executeDraftInspect(runtime, mailboxID, draftID)
		}
		patch, err := buildDraftEditPatch(runtime)
		if err != nil {
			return err
		}
		rawDraft, err := draftpkg.GetRaw(runtime, mailboxID, draftID)
		if err != nil {
			return fmt.Errorf("read draft raw EML failed: %w", err)
		}
		snapshot, err := draftpkg.Parse(rawDraft)
		if err != nil {
			return output.ErrValidation("parse draft raw EML failed: %v", err)
		}
		// Pre-process ops that need snapshot context: resolve signature using
		// the draft's From address, and build ICS for set_calendar using the
		// draft's From/To/Cc so organizer and attendee addresses are correct.
		var draftFromEmail string
		if len(snapshot.From) > 0 {
			draftFromEmail = snapshot.From[0].Address
		}
		if err := requireSenderForRequestReceipt(runtime, draftFromEmail); err != nil {
			return err
		}
		if runtime.Bool("request-receipt") {
			// draftFromEmail comes from the existing draft's From header,
			// which could have been authored via a raw-EML path (IMAP APPEND,
			// OpenAPI drafts raw) and contain CR/LF or dangerous Unicode.
			// Going straight into PatchOp.Value would bypass emlbuilder's
			// validateHeaderValue gate, so repeat the check here explicitly.
			if err := validateHeaderAddress(draftFromEmail); err != nil {
				return output.ErrValidation(
					"cannot set --request-receipt: draft From address is unsafe for a header (%v)", err)
			}
			patch.Ops = append(patch.Ops, draftpkg.PatchOp{
				Op:    "set_header",
				Name:  "Disposition-Notification-To",
				Value: "<" + draftFromEmail + ">",
			})
		}
		for i := range patch.Ops {
			switch patch.Ops[i].Op {
			case "insert_signature":
				sigResult, sigErr := resolveSignature(ctx, runtime, mailboxID, patch.Ops[i].SignatureID, draftFromEmail)
				if sigErr != nil {
					return sigErr
				}
				if sigResult != nil {
					patch.Ops[i].RenderedSignatureHTML = sigResult.RenderedContent
					patch.Ops[i].SignatureImages = sigResult.Images
				}
			case "set_calendar":
				if calPart := draftpkg.FindPartByMediaType(snapshot.Body, "text/calendar"); calPart != nil {
					parsed := ics.ParseEvent(string(calPart.Body))
					if parsed == nil || !parsed.IsLarkDraft {
						return output.ErrValidation("set_calendar: calendar event has already been created and is read-only; use --remove-event to remove it, then --set-event-* to create a new one")
					}
				}
				if _, _, err := parseEventTimeRange(patch.Ops[i].EventStart, patch.Ops[i].EventEnd); err != nil {
					return output.ErrValidation("set_calendar: %v", err)
				}
				// Derive effective To/Cc by replaying all pending recipient ops so
				// the ICS ATTENDEE list matches the final post-edit recipients.
				toAddrs, ccAddrs := effectiveRecipients(snapshot, patch.Ops)
				calData := buildCalendarBodyFromArgs(
					patch.Ops[i].EventSummary,
					patch.Ops[i].EventStart,
					patch.Ops[i].EventEnd,
					patch.Ops[i].EventLocation,
					draftFromEmail,
					joinAddresses(toAddrs),
					joinAddresses(ccAddrs),
				)
				if calData == nil {
					return output.ErrValidation("set_calendar: failed to build ICS from event fields")
				}
				patch.Ops[i].CalendarICS = calData
			}
		}
		// Pre-process add_attachment ops for large attachment support:
		// extract oversized files, upload them, inject HTML into the snapshot body.
		patch, err = preprocessLargeAttachmentsForDraftEdit(ctx, runtime, snapshot, patch)
		if err != nil {
			return err
		}
		// Writing-path lint for body ops only: set_body / set_reply_body
		// rewrite the body field; other ops (set_subject / set_recipients /
		// add_attachment / etc.) operate on non-HTML fields and MUST NOT be
		// linted. Lint runs after loadPatchFile parses JSON and BEFORE
		// draftpkg.Apply writes into the snapshot. Each op's `value` is
		// replaced with the cleaned HTML in place; findings accumulate across
		// ops into a single per-patch report.
		lintApplied, lintBlocked := emptyLintEnvelopeFields()
		for i := range patch.Ops {
			op := &patch.Ops[i]
			if op.Op != "set_body" && op.Op != "set_reply_body" {
				continue
			}
			if op.Value == "" {
				continue
			}
			if !bodyIsHTML(op.Value) {
				// Plain-text body op — no lint pass needed (the HTML rule set
				// is irrelevant), but the envelope still surfaces empty arrays.
				continue
			}
			cleaned, rep := runWritePathLint(op.Value)
			op.Value = cleaned
			lintApplied = append(lintApplied, rep.Applied...)
			lintBlocked = append(lintBlocked, rep.Blocked...)
		}
		dctx := &draftpkg.DraftCtx{FIO: runtime.FileIO()}
		if len(patch.Ops) > 0 {
			if err := draftpkg.Apply(dctx, snapshot, patch); err != nil {
				return output.ErrValidation("apply draft patch failed: %v", err)
			}
		}
		serialized, err := draftpkg.Serialize(snapshot)
		if err != nil {
			return output.ErrValidation("serialize draft failed: %v", err)
		}
		updateResult, err := draftpkg.UpdateWithRaw(runtime, mailboxID, draftID, serialized)
		if err != nil {
			return fmt.Errorf("update draft failed: %w", err)
		}
		projection := draftpkg.Project(snapshot)
		out := map[string]interface{}{
			"draft_id":   updateResult.DraftID,
			"warning":    "This edit flow has no optimistic locking. If the same draft is changed concurrently, the last writer wins.",
			"projection": projection,
		}
		if updateResult.Reference != "" {
			out["reference"] = updateResult.Reference
		}
		// Writing-path lint envelope: counts always present; full Finding
		// arrays only when the caller asked for them via --show-lint-details.
		applyLintToEnvelope(out, lintApplied, lintBlocked, runtime.Bool("show-lint-details"))
		addComposeHint(out)
		runtime.OutFormat(out, nil, func(w io.Writer) {
			fmt.Fprintln(w, "Draft updated.")
			fmt.Fprintf(w, "draft_id: %s\n", updateResult.DraftID)
			if reference, _ := out["reference"].(string); reference != "" {
				fmt.Fprintf(w, "reference: %s\n", reference)
			}
			if projection.Subject != "" {
				fmt.Fprintf(w, "subject: %s\n", sanitizeForTerminal(projection.Subject))
			}
			if recipients := prettyDraftAddresses(projection.To); recipients != "" {
				fmt.Fprintf(w, "to: %s\n", sanitizeForTerminal(recipients))
			}
			if projection.BodyText != "" {
				fmt.Fprintf(w, "body_text: %s\n", sanitizeForTerminal(projection.BodyText))
			}
			if projection.BodyHTMLSummary != "" {
				fmt.Fprintf(w, "body_html_summary: %s\n", sanitizeForTerminal(projection.BodyHTMLSummary))
			}
			if len(projection.AttachmentsSummary) > 0 {
				fmt.Fprintf(w, "attachments: %d\n", len(projection.AttachmentsSummary))
			}
			if len(projection.InlineSummary) > 0 {
				fmt.Fprintf(w, "inline_parts: %d\n", len(projection.InlineSummary))
			}
			if len(projection.Warnings) > 0 {
				fmt.Fprintf(w, "warnings: %s\n", sanitizeForTerminal(strings.Join(projection.Warnings, "; ")))
			}
			fmt.Fprintln(w, "warning: This edit flow has no optimistic locking. If the same draft is changed concurrently, the last writer wins.")
		})
		return nil
	},
}

// executeDraftInspect implements the +draft-edit --inspect path: it fetches
// the raw EML, parses it into a MIME snapshot, and emits a draft projection
// (subject, recipients, body summary, attachment / inline summaries) without
// modifying the draft.
func executeDraftInspect(runtime *common.RuntimeContext, mailboxID, draftID string) error {
	rawDraft, err := draftpkg.GetRaw(runtime, mailboxID, draftID)
	if err != nil {
		return fmt.Errorf("read draft raw EML failed: %w", err)
	}
	snapshot, err := draftpkg.Parse(rawDraft)
	if err != nil {
		return output.ErrValidation("parse draft raw EML failed: %v", err)
	}
	projection := draftpkg.Project(snapshot)
	out := map[string]interface{}{
		"draft_id":   draftID,
		"projection": projection,
	}
	runtime.OutFormat(out, nil, func(w io.Writer) {
		fmt.Fprintln(w, "Draft inspection (read-only, no changes applied).")
		fmt.Fprintf(w, "draft_id: %s\n", draftID)
		if projection.Subject != "" {
			fmt.Fprintf(w, "subject: %s\n", sanitizeForTerminal(projection.Subject))
		}
		if recipients := prettyDraftAddresses(projection.To); recipients != "" {
			fmt.Fprintf(w, "to: %s\n", sanitizeForTerminal(recipients))
		}
		if recipients := prettyDraftAddresses(projection.Cc); recipients != "" {
			fmt.Fprintf(w, "cc: %s\n", sanitizeForTerminal(recipients))
		}
		if projection.BodyText != "" {
			fmt.Fprintf(w, "body_text: %s\n", sanitizeForTerminal(projection.BodyText))
		}
		if projection.BodyHTMLSummary != "" {
			fmt.Fprintf(w, "body_html_summary: %s\n", sanitizeForTerminal(projection.BodyHTMLSummary))
		}
		if projection.HasQuotedContent {
			fmt.Fprintln(w, "has_quoted_content: true (use set_reply_body op in --patch-file to edit body while preserving the quote)")
		}
		if len(projection.AttachmentsSummary) > 0 {
			fmt.Fprintf(w, "attachments (%d):\n", len(projection.AttachmentsSummary))
			for _, att := range projection.AttachmentsSummary {
				fmt.Fprintf(w, "  - part_id=%s  filename=%s  content_type=%s  cid=%s\n",
					att.PartID, att.FileName, att.ContentType, att.CID)
			}
		}
		if len(projection.LargeAttachmentsSummary) > 0 {
			fmt.Fprintf(w, "large_attachments (%d):\n", len(projection.LargeAttachmentsSummary))
			for _, att := range projection.LargeAttachmentsSummary {
				fmt.Fprintf(w, "  - token=%s  filename=%s  size_bytes=%d\n",
					att.Token, att.FileName, att.SizeBytes)
			}
		}
		if len(projection.InlineSummary) > 0 {
			fmt.Fprintf(w, "inline_parts (%d):\n", len(projection.InlineSummary))
			for _, inl := range projection.InlineSummary {
				fmt.Fprintf(w, "  - part_id=%s  filename=%s  content_type=%s  cid=%s\n",
					inl.PartID, inl.FileName, inl.ContentType, inl.CID)
			}
		}
		if len(projection.Warnings) > 0 {
			fmt.Fprintf(w, "warnings: %s\n", sanitizeForTerminal(strings.Join(projection.Warnings, "; ")))
		}
		if projection.Priority != "" {
			fmt.Fprintf(w, "priority: %s\n", sanitizeForTerminal(projection.Priority))
		}
	})
	return nil
}

// prettyDraftAddresses renders a list of draft addresses as a comma-separated
// string suitable for stderr human output. Returns "" for an empty list.
func prettyDraftAddresses(addrs []draftpkg.Address) string {
	if len(addrs) == 0 {
		return ""
	}
	parts := make([]string, 0, len(addrs))
	for _, addr := range addrs {
		parts = append(parts, addr.String())
	}
	return strings.Join(parts, ", ")
}

// buildDraftEditPatch assembles a draftpkg.Patch from the runtime flags:
// direct flags (--set-subject / --set-to / --set-cc / --set-bcc /
// --set-priority) become Ops, and --patch-file is loaded and merged.
// Returns ErrValidation when neither direct flags nor --patch-file produce
// any operations.
func buildDraftEditPatch(runtime *common.RuntimeContext) (draftpkg.Patch, error) {
	patch := draftpkg.Patch{
		Options: draftpkg.PatchOptions{
			AllowProtectedHeaderEdits: runtime.Bool("allow-protected-header-edit"),
			RewriteEntireDraft:        runtime.Bool("rewrite-entire-draft"),
		},
	}

	patchFile := strings.TrimSpace(runtime.Str("patch-file"))
	if patchFile != "" {
		filePatch, err := loadPatchFile(runtime, patchFile)
		if err != nil {
			return patch, err
		}
		patch.Ops = append(patch.Ops, filePatch.Ops...)
		if filePatch.Options.AllowProtectedHeaderEdits {
			patch.Options.AllowProtectedHeaderEdits = true
		}
		if filePatch.Options.RewriteEntireDraft {
			patch.Options.RewriteEntireDraft = true
		}
	}

	setRecipients := func(field, raw string) {
		if strings.TrimSpace(raw) == "" {
			return
		}
		addrs := parseNetAddrs(raw)
		opAddrs := make([]draftpkg.Address, 0, len(addrs))
		for _, addr := range addrs {
			opAddrs = append(opAddrs, draftpkg.Address{
				Name:    addr.Name,
				Address: addr.Address,
			})
		}
		patch.Ops = append(patch.Ops, draftpkg.PatchOp{
			Op:        "set_recipients",
			Field:     field,
			Addresses: opAddrs,
		})
	}

	if value := strings.TrimSpace(runtime.Str("set-subject")); value != "" {
		patch.Ops = append(patch.Ops, draftpkg.PatchOp{Op: "set_subject", Value: value})
	}
	if err := validateRecipientCount(runtime.Str("set-to"), runtime.Str("set-cc"), runtime.Str("set-bcc")); err != nil {
		return patch, err
	}
	setRecipients("to", runtime.Str("set-to"))
	setRecipients("cc", runtime.Str("set-cc"))
	setRecipients("bcc", runtime.Str("set-bcc"))

	// --body / --body-file are convenience shorthands for a set_body patch
	// op. They cannot be combined with --patch-file body ops
	// (set_body / set_reply_body) to avoid ambiguous ordering.
	bodyFlag := runtime.Str("body")
	bodyFile := strings.TrimSpace(runtime.Str("body-file"))
	if err := validateBodyFileMutex(bodyFlag, bodyFile, runtime.ValidatePath); err != nil {
		return patch, err
	}
	bodyVal := bodyFlag
	if bodyVal == "" && bodyFile != "" {
		loaded, err := readBodyFile(runtime.FileIO(), bodyFile)
		if err != nil {
			return patch, err
		}
		bodyVal = loaded
	}
	if bodyVal != "" {
		for _, op := range patch.Ops {
			if op.Op == "set_body" || op.Op == "set_reply_body" {
				return patch, output.ErrValidation("--body / --body-file and --patch-file body ops (set_body/set_reply_body) are mutually exclusive; use one or the other")
			}
		}
		patch.Ops = append(patch.Ops, draftpkg.PatchOp{Op: "set_body", Value: bodyVal})
	}

	// --set-priority → inject set_header / remove_header op
	if setPriority := runtime.Str("set-priority"); setPriority != "" {
		headerVal, pErr := parsePriority(setPriority)
		if pErr != nil {
			return patch, pErr
		}
		if headerVal != "" {
			patch.Ops = append(patch.Ops, draftpkg.PatchOp{Op: "set_header", Name: "X-Cli-Priority", Value: headerVal})
		} else {
			patch.Ops = append(patch.Ops, draftpkg.PatchOp{Op: "remove_header", Name: "X-Cli-Priority"})
		}
	}

	// --set-event-* / --remove-event → set_calendar / remove_calendar op.
	// The ICS blob itself is pre-built at Execute time once the snapshot's
	// organizer/attendee addresses are available; here we only record the
	// user-supplied fields and validate the flag combination.
	hasEventSet := runtime.Str("set-event-summary") != ""
	hasEventRemove := runtime.Bool("remove-event")
	if !hasEventSet && (runtime.Str("set-event-start") != "" || runtime.Str("set-event-end") != "" || runtime.Str("set-event-location") != "") {
		return patch, output.ErrValidation("--set-event-start, --set-event-end, and --set-event-location require --set-event-summary")
	}
	if hasEventSet && hasEventRemove {
		return patch, output.ErrValidation("--set-event-summary and --remove-event are mutually exclusive")
	}
	if hasEventSet {
		summary := runtime.Str("set-event-summary")
		start := runtime.Str("set-event-start")
		end := runtime.Str("set-event-end")
		if summary == "" || start == "" || end == "" {
			return patch, output.ErrValidation("--set-event-summary, --set-event-start, and --set-event-end must all be provided together")
		}
		if _, _, err := parseEventTimeRange(start, end); err != nil {
			return patch, output.ErrValidation("%s", prefixEventRangeError("--set-event-", err).Error())
		}
		patch.Ops = append(patch.Ops, draftpkg.PatchOp{
			Op:            "set_calendar",
			EventSummary:  summary,
			EventStart:    start,
			EventEnd:      end,
			EventLocation: runtime.Str("set-event-location"),
		})
	} else if hasEventRemove {
		patch.Ops = append(patch.Ops, draftpkg.PatchOp{Op: "remove_calendar"})
	}

	if len(patch.Ops) == 0 && !runtime.Bool("request-receipt") {
		return patch, output.ErrValidation("at least one edit operation is required; use direct flags such as --set-subject/--set-to, or use --patch-file for body edits and other advanced operations (run --print-patch-template first)")
	}
	if len(patch.Ops) == 0 {
		// --request-receipt only: Validate() would reject empty Ops, so skip it
		// here. The Disposition-Notification-To op is appended in Execute once
		// the draft's From address is known.
		return patch, nil
	}
	return patch, patch.Validate()
}

// loadPatchFile reads and JSON-decodes a patch file from a relative path
// rooted at the runtime's FileIO. Returns ErrValidation on read or parse
// errors so the caller can surface a user-friendly message without leaking
// internal stack traces.
func loadPatchFile(runtime *common.RuntimeContext, path string) (draftpkg.Patch, error) {
	var patch draftpkg.Patch
	f, err := runtime.FileIO().Open(path)
	if err != nil {
		return patch, fmt.Errorf("--patch-file %q: %w", path, err)
	}
	defer f.Close()
	data, err := io.ReadAll(f)
	if err != nil {
		return patch, err
	}
	if err := json.Unmarshal(data, &patch); err != nil {
		return patch, fmt.Errorf("parse patch file: %w", err)
	}
	return patch, patch.Validate()
}

// buildDraftEditPatchTemplate returns the JSON template emitted by
// --print-patch-template. It documents the supported ops and field shapes so
// callers can author a --patch-file without having to read this file's source.
func buildDraftEditPatchTemplate() map[string]interface{} {
	return map[string]interface{}{
		"description": "Typed patch JSON for `mail +draft-edit --patch-file`. This is not RFC 6902 JSON Patch.",
		"template": map[string]interface{}{
			"ops": []map[string]interface{}{
				{"op": "set_subject", "value": "Updated subject"},
				{"op": "set_recipients", "field": "to", "addresses": []map[string]interface{}{{"address": "alice@example.com", "name": "Alice"}}},
				{"op": "set_body", "value": "Updated body"},
			},
			"options": map[string]interface{}{
				"rewrite_entire_draft":         false,
				"allow_protected_header_edits": false,
			},
		},
		"options_help": map[string]interface{}{
			"rewrite_entire_draft":         "Default false. Set to true only when the edit must synthesize or restructure body parts, for example adding a missing primary body part.",
			"allow_protected_header_edits": "Default false. Set to true only when the user explicitly wants to edit protected headers and understands the threading or delivery risk.",
		},
		"supported_ops": []map[string]interface{}{
			{"op": "set_subject", "shape": map[string]interface{}{"value": "string"}},
			{"op": "set_recipients", "shape": map[string]interface{}{"field": "to|cc|bcc", "addresses": []map[string]interface{}{{"address": "string", "name": "string(optional)"}}}},
			{"op": "add_recipient", "shape": map[string]interface{}{"field": "to|cc|bcc", "address": "string", "name": "string(optional)"}},
			{"op": "remove_recipient", "shape": map[string]interface{}{"field": "to|cc|bcc", "address": "string"}},
			{"op": "set_body", "shape": map[string]interface{}{"value": "string (supports <img src=\"./local/path.png\" /> — local paths auto-resolved to inline MIME parts)"}},
			{"op": "set_reply_body", "shape": map[string]interface{}{"value": "string (user-authored content only, WITHOUT the quote block; quote block, signature, and attachment cards are auto-preserved; supports <img src=\"./local/path.png\" /> — local paths auto-resolved to inline MIME parts)"}},
			{"op": "set_header", "shape": map[string]interface{}{"name": "string", "value": "string"}},
			{"op": "remove_header", "shape": map[string]interface{}{"name": "string"}},
			{"op": "add_attachment", "shape": map[string]interface{}{"path": "string(relative path)"}},
			{"op": "remove_attachment", "shape": map[string]interface{}{"target": map[string]interface{}{"part_id": "string(optional, for normal attachment)", "cid": "string(optional, for normal attachment)", "token": "string(optional, for large attachment; from large_attachments_summary in --inspect)"}}},
			{"op": "add_inline", "shape": map[string]interface{}{"path": "string(relative path)", "cid": "string", "filename": "string(optional)", "content_type": "string(optional)"}, "note": "advanced: prefer <img src=\"./path\"> in set_body/set_reply_body instead"},
			{"op": "replace_inline", "shape": map[string]interface{}{"target": map[string]interface{}{"part_id": "string(optional)", "cid": "string(optional)"}, "path": "string(relative path)", "cid": "string(optional)", "filename": "string(optional)", "content_type": "string(optional)"}},
			{"op": "remove_inline", "shape": map[string]interface{}{"target": map[string]interface{}{"part_id": "string(optional)", "cid": "string(optional)"}}},
			{"op": "insert_signature", "shape": map[string]interface{}{"signature_id": "string (run mail +signature to list IDs)"}},
			{"op": "remove_signature", "shape": map[string]interface{}{}, "note": "removes existing signature from the HTML body"},
		},
		"supported_ops_by_group": []map[string]interface{}{
			{
				"group": "subject_and_body",
				"ops": []map[string]interface{}{
					{"op": "set_subject", "shape": map[string]interface{}{"value": "string"}},
					{"op": "set_body", "shape": map[string]interface{}{"value": "string (supports <img src=\"./local/path.png\" /> — local paths auto-resolved to inline MIME parts)"}},
					{"op": "set_reply_body", "shape": map[string]interface{}{"value": "string (user-authored content only, WITHOUT the quote block; quote block, signature, and attachment cards are auto-preserved; supports <img src=\"./local/path.png\" /> — local paths auto-resolved to inline MIME parts)"}},
				},
			},
			{
				"group": "recipients",
				"ops": []map[string]interface{}{
					{"op": "set_recipients", "shape": map[string]interface{}{"field": "to|cc|bcc", "addresses": []map[string]interface{}{{"address": "string", "name": "string(optional)"}}}},
					{"op": "add_recipient", "shape": map[string]interface{}{"field": "to|cc|bcc", "address": "string", "name": "string(optional)"}},
					{"op": "remove_recipient", "shape": map[string]interface{}{"field": "to|cc|bcc", "address": "string"}},
				},
			},
			{
				"group": "headers",
				"ops": []map[string]interface{}{
					{"op": "set_header", "shape": map[string]interface{}{"name": "string", "value": "string"}},
					{"op": "remove_header", "shape": map[string]interface{}{"name": "string"}},
				},
			},
			{
				"group": "attachments_and_inline",
				"ops": []map[string]interface{}{
					{"op": "add_attachment", "shape": map[string]interface{}{"path": "string(relative path)"}},
					{"op": "remove_attachment", "shape": map[string]interface{}{"target": map[string]interface{}{"part_id": "string(optional, for normal attachment)", "cid": "string(optional, for normal attachment)", "token": "string(optional, for large attachment; from large_attachments_summary in --inspect)"}}},
					{"op": "add_inline", "shape": map[string]interface{}{"path": "string(relative path)", "cid": "string", "filename": "string(optional)", "content_type": "string(optional)"}, "note": "advanced: prefer <img src=\"./path\"> in set_body/set_reply_body instead"},
					{"op": "replace_inline", "shape": map[string]interface{}{"target": map[string]interface{}{"part_id": "string(optional)", "cid": "string(optional)"}, "path": "string(relative path)", "cid": "string(optional)", "filename": "string(optional)", "content_type": "string(optional)"}},
					{"op": "remove_inline", "shape": map[string]interface{}{"target": map[string]interface{}{"part_id": "string(optional)", "cid": "string(optional)"}}},
				},
			},
			{
				"group": "signature",
				"ops": []map[string]interface{}{
					{"op": "insert_signature", "shape": map[string]interface{}{"signature_id": "string (run mail +signature to list IDs)"}},
					{"op": "remove_signature", "shape": map[string]interface{}{}, "note": "removes existing signature and its preceding spacing from the HTML body"},
				},
			},
		},
		"recommended_usage": []string{
			"Use direct flags (--set-subject, --set-to, --set-cc, --set-bcc) for simple metadata edits",
			"Use --body/--body-file for quick full-body replacement; use --patch-file for advanced body edits and advanced changes (recipients, headers, attachments, inline images)",
			"Before editing body, run --inspect to check has_quoted_content; if true, use set_reply_body instead of set_body",
		},
		"body_edit_decision_guide": []map[string]interface{}{
			{"situation": "plain draft or non-reply/forward draft", "recommended_op": "set_body — replaces user-authored content; signature/attachments auto-preserved"},
			{"situation": "draft has both text/plain and text/html", "recommended_op": "set_body — updates HTML body and regenerates plain-text summary; pass HTML input because the original main body is text/html"},
			{"situation": "draft created by +reply or +forward (has_quoted_content=true)", "recommended_op": "set_reply_body — replaces only the user-authored portion; quote block, signature, and attachments are automatically preserved. Use set_body if user explicitly wants to remove or modify the quote"},
		},
		"notes": []string{
			"`set_body`/`set_reply_body` support inline images via local file paths: use <img src=\"./local/file.png\" /> in the HTML value — the local path is automatically resolved into an inline MIME part with a generated CID; removing or replacing an <img> tag automatically cleans up or replaces the corresponding MIME part; do NOT use `add_inline` for this; example: {\"op\":\"set_body\",\"value\":\"<div>Hello<img src=\\\"./logo.png\\\" /></div>\"}",
			"`add_inline` is an advanced op for precise CID control only — in most cases, use <img src=\"./path\"> in `set_body`/`set_reply_body` instead",
			"`ops` is executed in order",
			"all file paths (--patch-file and `path` fields in ops) must be relative — no absolute paths or .. traversal",
			"use --body <html> for a quick full-body replacement (equivalent to a set_body op); use --patch-file with set_body/set_reply_body for advanced body edits; --body and --patch-file body ops are mutually exclusive",
			"`set_body` replaces the user-authored content. It does NOT auto-preserve the old quote block (include one in value if needed, or use `set_reply_body`). Signature, large attachment card, and normal attachment MIME parts are auto-preserved. When the draft has both text/plain and text/html, it updates the HTML body and regenerates the plain-text summary, so the input should be HTML.",
			"`set_reply_body` replaces only the user-authored portion of the body and automatically re-appends the trailing reply/forward quote block, signature, and large attachment card; the value you pass should contain ONLY the new user-authored content (no quote, no signature, no attachment card). If the user wants to modify content INSIDE the quote block, use `set_body` instead. If the draft has no quote block, it behaves identically to `set_body`.",
			"`body_kind` only supports text/plain and text/html",
			"`selector` currently only supports primary",
			"`remove_attachment` target supports part_id (normal attachment), cid (normal attachment), or token (large attachment); priority: part_id > cid > token",
			"Large attachments are located by token (not part_id/cid). Get tokens from `--inspect`'s `large_attachments_summary`.",
			"`set_body` and `set_reply_body` automatically preserve signature block and all attachments (normal + large) from the old body. To delete signature/attachments use the dedicated ops: remove_signature, remove_attachment.",
			"`remove_attachment`/`remove_inline` require part_id or cid; to discover these values, run `+draft-edit --draft-id <id> --inspect` first — the response `projection.attachments_summary` and `projection.inline_summary` list every part with its part_id, cid, and filename",
			"`add_inline`/`replace_inline`/`remove_inline` are for CID-based inline images",
			"`replace_inline` keeps the original filename and content_type when those fields are omitted",
			"protected headers require `allow_protected_header_edits=true`",
			"--set-priority high|normal|low controls draft priority via X-Cli-Priority header (CLI/OAPI specific). high → set_header X-Cli-Priority=1; low → set_header X-Cli-Priority=5; normal → remove_header X-Cli-Priority. Backend mail-data-access headersToPbBodyExtra recognizes X-Cli-Priority but not standard X-Priority/Importance for OAPI flow.",
		},
		"command_example":    "lark-cli mail +draft-edit --print-patch-template",
		"patch_file_example": "lark-cli mail +draft-edit --draft-id d_xxx --patch-file ./patch.json",
	}
}

// effectiveRecipients returns the To and Cc address slices that will result
// after all pending set_recipients / add_recipient / remove_recipient ops in
// ops have been applied. Used by the set_calendar pre-processor to build ICS
// with the correct post-edit ATTENDEE list before Apply() runs.
func effectiveRecipients(snapshot *draftpkg.DraftSnapshot, ops []draftpkg.PatchOp) (to, cc []draftpkg.Address) {
	to = append([]draftpkg.Address{}, snapshot.To...)
	cc = append([]draftpkg.Address{}, snapshot.Cc...)

	apply := func(addrs []draftpkg.Address, op draftpkg.PatchOp) []draftpkg.Address {
		switch op.Op {
		case "set_recipients":
			return append([]draftpkg.Address{}, op.Addresses...)
		case "add_recipient":
			for _, a := range addrs {
				if strings.EqualFold(a.Address, op.Address) {
					return addrs
				}
			}
			return append(addrs, draftpkg.Address{Name: op.Name, Address: op.Address})
		case "remove_recipient":
			next := addrs[:0:0]
			for _, a := range addrs {
				if !strings.EqualFold(a.Address, op.Address) {
					next = append(next, a)
				}
			}
			return next
		}
		return addrs
	}

	for _, op := range ops {
		switch op.Field {
		case "to":
			to = apply(to, op)
		case "cc":
			cc = apply(cc, op)
		}
	}
	return to, cc
}