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

package markdown

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"net/http"
	"path"
	"path/filepath"
	"strings"

	larkcore "github.com/larksuite/oapi-sdk-go/v3/core"

	"github.com/larksuite/cli/errs"
	"github.com/larksuite/cli/internal/output"
	"github.com/larksuite/cli/internal/validate"
	"github.com/larksuite/cli/shortcuts/common"
)

const markdownSinglePartSizeLimit = common.MaxDriveMediaUploadSinglePartSize
const markdownEmptyContentError = "empty markdown content is not supported; cannot create or overwrite an empty file"

const (
	markdownUploadParentTypeExplorer = "explorer"
	markdownUploadParentTypeWiki     = "wiki"
)

type markdownUploadSpec struct {
	FileToken   string
	FileName    string
	FolderToken string
	WikiToken   string
	FilePath    string
	Content     string
	ContentSet  bool
	FileSet     bool
}

type markdownUploadResult struct {
	FileToken string
	Version   string
}

type markdownMultipartSession struct {
	UploadID  string
	BlockSize int64
	BlockNum  int
}

type markdownUploadTarget struct {
	ParentType string
	ParentNode string
}

func (spec markdownUploadSpec) Target() markdownUploadTarget {
	if spec.WikiToken != "" {
		return markdownUploadTarget{
			ParentType: markdownUploadParentTypeWiki,
			ParentNode: spec.WikiToken,
		}
	}
	// An empty explorer parent node uploads to the user's Drive root folder.
	return markdownUploadTarget{
		ParentType: markdownUploadParentTypeExplorer,
		ParentNode: spec.FolderToken,
	}
}

func validateMarkdownSpec(runtime *common.RuntimeContext, spec markdownUploadSpec, requireName bool) error {
	switch {
	case spec.ContentSet && spec.FileSet:
		return common.FlagErrorf("--content and --file are mutually exclusive")
	case !spec.ContentSet && !spec.FileSet:
		return common.FlagErrorf("specify exactly one of --content or --file")
	}

	if markdownFlagExplicitlyEmpty(runtime, "folder-token") {
		return common.FlagErrorf("--folder-token cannot be empty; omit it to upload into Drive root folder")
	}
	if markdownFlagExplicitlyEmpty(runtime, "wiki-token") {
		return common.FlagErrorf("--wiki-token cannot be empty; provide a valid wiki node token or omit the flag entirely")
	}
	targets := 0
	if spec.FolderToken != "" {
		targets++
	}
	if spec.WikiToken != "" {
		targets++
	}
	if targets > 1 {
		return common.FlagErrorf("--folder-token and --wiki-token are mutually exclusive")
	}
	if spec.FolderToken != "" {
		if err := validate.ResourceName(spec.FolderToken, "--folder-token"); err != nil {
			return output.ErrValidation("%s", err)
		}
	}
	if spec.WikiToken != "" {
		if err := validate.ResourceName(spec.WikiToken, "--wiki-token"); err != nil {
			return output.ErrValidation("%s", err)
		}
	}

	if requireName && spec.ContentSet {
		if strings.TrimSpace(spec.FileName) == "" {
			return common.FlagErrorf("--name is required when using --content")
		}
		if err := validateMarkdownFileName(spec.FileName, "--name"); err != nil {
			return err
		}
	}

	if spec.FileSet {
		if strings.TrimSpace(spec.FilePath) == "" {
			return common.FlagErrorf("--file cannot be empty")
		}
		if _, err := validate.SafeInputPath(spec.FilePath); err != nil {
			return output.ErrValidation("unsafe file path: %s", err)
		}
		if err := validateMarkdownFileName(filepath.Base(spec.FilePath), "--file"); err != nil {
			return err
		}
	}

	if spec.FileName != "" {
		if err := validateMarkdownFileName(spec.FileName, "--name"); err != nil {
			return err
		}
	}

	return nil
}

func markdownFlagExplicitlyEmpty(runtime *common.RuntimeContext, flagName string) bool {
	return runtime.Changed(flagName) && strings.TrimSpace(runtime.Str(flagName)) == ""
}

func validateMarkdownFileName(name, flagName string) error {
	trimmed := strings.TrimSpace(name)
	if trimmed == "" {
		return common.FlagErrorf("%s cannot be empty", flagName)
	}
	if !strings.HasSuffix(strings.ToLower(trimmed), ".md") {
		return common.FlagErrorf("%s must end with .md", flagName)
	}
	return nil
}

func finalMarkdownFileName(spec markdownUploadSpec) string {
	if strings.TrimSpace(spec.FileName) != "" {
		return strings.TrimSpace(spec.FileName)
	}
	if strings.TrimSpace(spec.FilePath) == "" {
		return ""
	}
	return filepath.Base(spec.FilePath)
}

func resolveMarkdownOverwriteFileName(runtime *common.RuntimeContext, spec markdownUploadSpec) (string, error) {
	fileName := strings.TrimSpace(spec.FileName)
	if fileName == "" && spec.FileSet {
		fileName = filepath.Base(spec.FilePath)
	}
	if fileName == "" {
		remoteName, err := fetchMarkdownFileName(runtime, spec.FileToken)
		if err != nil {
			return "", err
		}
		fileName = strings.TrimSpace(remoteName)
	}
	if fileName == "" {
		fileName = spec.FileToken + ".md"
	}
	return fileName, nil
}

func openMarkdownDownload(ctx context.Context, runtime *common.RuntimeContext, fileToken string) (*http.Response, error) {
	resp, err := runtime.DoAPIStream(ctx, &larkcore.ApiReq{
		HttpMethod: http.MethodGet,
		ApiPath:    fmt.Sprintf("/open-apis/drive/v1/files/%s/download", validate.EncodePathSegment(fileToken)),
	})
	if err != nil {
		return nil, wrapMarkdownDownloadError(err)
	}
	return resp, nil
}

func wrapMarkdownDownloadError(err error) error {
	// Preserve any already-classified error: legacy *output.ExitError or any
	// typed errs.* error. Only un-classified errors get wrapped as network.
	var exitErr *output.ExitError
	if errors.As(err, &exitErr) {
		return err
	}
	if _, ok := errs.ProblemOf(err); ok {
		return err
	}
	return output.ErrNetwork("download failed: %s", err)
}

func validateNonEmptyMarkdownSize(size int64) error {
	if size == 0 {
		return output.ErrValidation("%s", markdownEmptyContentError)
	}
	return nil
}

func markdownSourceSize(runtime *common.RuntimeContext, spec markdownUploadSpec) (int64, error) {
	var size int64
	if spec.ContentSet {
		size = int64(len(spec.Content))
	} else {
		if strings.TrimSpace(spec.FilePath) == "" {
			return 0, common.FlagErrorf("--file cannot be empty")
		}

		info, err := runtime.FileIO().Stat(spec.FilePath)
		if err != nil {
			return 0, common.WrapInputStatError(err)
		}
		size = info.Size()
	}
	if err := validateNonEmptyMarkdownSize(size); err != nil {
		return 0, err
	}
	return size, nil
}

func openMarkdownDownloadVersion(ctx context.Context, runtime *common.RuntimeContext, fileToken, version string) (*http.Response, string, error) {
	req := &larkcore.ApiReq{
		HttpMethod: http.MethodGet,
		ApiPath:    fmt.Sprintf("/open-apis/drive/v1/files/%s/download", validate.EncodePathSegment(fileToken)),
	}
	if strings.TrimSpace(version) != "" {
		req.QueryParams = larkcore.QueryParams{
			"version": []string{strings.TrimSpace(version)},
		}
	}

	resp, err := runtime.DoAPIStream(ctx, req)
	if err != nil {
		return nil, "", wrapMarkdownDownloadError(err)
	}
	return resp, fileNameFromDownloadHeader(resp.Header, fileToken+".md"), nil
}

func markdownDryRunFileField(spec markdownUploadSpec) string {
	if spec.FilePath != "" {
		return "@" + spec.FilePath
	}
	return "<markdown content>"
}

func markdownUploadDryRun(spec markdownUploadSpec, fileSize int64, multipart bool) *common.DryRunAPI {
	fileName := finalMarkdownFileName(spec)
	target := spec.Target()

	if !multipart {
		body := map[string]interface{}{
			"file_name":   fileName,
			"parent_type": target.ParentType,
			"parent_node": target.ParentNode,
			"size":        fileSize,
			"file":        markdownDryRunFileField(spec),
		}
		if spec.FileToken != "" {
			body["file_token"] = spec.FileToken
		}

		desc := "multipart/form-data upload"
		if spec.FileToken != "" {
			desc = "multipart/form-data overwrite upload"
		}

		return common.NewDryRunAPI().
			Desc(desc).
			POST("/open-apis/drive/v1/files/upload_all").
			Body(body)
	}

	prepareBody := map[string]interface{}{
		"file_name":   fileName,
		"parent_type": target.ParentType,
		"parent_node": target.ParentNode,
		"size":        fileSize,
	}
	if spec.FileToken != "" {
		prepareBody["file_token"] = spec.FileToken
	}

	desc := "3-step multipart upload"
	if spec.FileToken != "" {
		desc = "3-step multipart overwrite upload"
	}

	return common.NewDryRunAPI().
		Desc(desc).
		POST("/open-apis/drive/v1/files/upload_prepare").
		Desc("[1] Initialize multipart upload").
		Body(prepareBody).
		POST("/open-apis/drive/v1/files/upload_part").
		Desc("[2] Upload file parts (repeated)").
		Body(map[string]interface{}{
			"upload_id": "<upload_id>",
			"seq":       "<chunk_index>",
			"size":      "<chunk_size>",
			"file":      "<chunk_binary>",
		}).
		POST("/open-apis/drive/v1/files/upload_finish").
		Desc("[3] Finalize upload and get file_token/version").
		Body(map[string]interface{}{
			"upload_id": "<upload_id>",
			"block_num": "<block_num>",
		})
}

func markdownOverwriteDryRun(spec markdownUploadSpec, fileSize int64, multipart bool) *common.DryRunAPI {
	fileName := strings.TrimSpace(spec.FileName)
	target := spec.Target()
	if fileName == "" && spec.FileSet {
		fileName = finalMarkdownFileName(spec)
	}
	if fileName != "" {
		spec.FileName = fileName
		return markdownUploadDryRun(spec, fileSize, multipart)
	}

	dry := common.NewDryRunAPI().Desc("Fetch the existing file name, then overwrite the file content")
	dry.POST("/open-apis/drive/v1/metas/batch_query").
		Desc("[1] Read current file metadata to preserve the existing file name").
		Body(map[string]interface{}{
			"request_docs": []map[string]interface{}{
				{
					"doc_token": spec.FileToken,
					"doc_type":  "file",
				},
			},
		})

	spec.FileName = "<existing_remote_name_or_" + spec.FileToken + ".md>"
	if !multipart {
		dry.POST("/open-apis/drive/v1/files/upload_all").
			Desc("[2] Overwrite file contents with multipart/form-data upload").
			Body(map[string]interface{}{
				"file_name":   spec.FileName,
				"parent_type": target.ParentType,
				"parent_node": target.ParentNode,
				"size":        fileSize,
				"file":        markdownDryRunFileField(spec),
				"file_token":  spec.FileToken,
			})
		return dry
	}

	dry.POST("/open-apis/drive/v1/files/upload_prepare").
		Desc("[2] Initialize multipart overwrite upload").
		Body(map[string]interface{}{
			"file_name":   spec.FileName,
			"parent_type": target.ParentType,
			"parent_node": target.ParentNode,
			"size":        fileSize,
			"file_token":  spec.FileToken,
		}).
		POST("/open-apis/drive/v1/files/upload_part").
		Desc("[3] Upload file parts (repeated)").
		Body(map[string]interface{}{
			"upload_id": "<upload_id>",
			"seq":       "<chunk_index>",
			"size":      "<chunk_size>",
			"file":      "<chunk_binary>",
		}).
		POST("/open-apis/drive/v1/files/upload_finish").
		Desc("[4] Finalize upload and get file_token/version").
		Body(map[string]interface{}{
			"upload_id": "<upload_id>",
			"block_num": "<block_num>",
		})
	return dry
}

func uploadMarkdownContent(runtime *common.RuntimeContext, spec markdownUploadSpec, payload []byte) (markdownUploadResult, error) {
	fileName := finalMarkdownFileName(spec)
	fileSize := int64(len(payload))
	if fileSize > markdownSinglePartSizeLimit {
		return uploadMarkdownFileMultipart(runtime, spec, bytes.NewReader(payload), fileName, fileSize)
	}
	return uploadMarkdownFileAll(runtime, spec, bytes.NewReader(payload), fileName, fileSize)
}

func uploadMarkdownLocalFile(runtime *common.RuntimeContext, spec markdownUploadSpec, fileSize int64) (markdownUploadResult, error) {
	fileName := finalMarkdownFileName(spec)
	f, err := runtime.FileIO().Open(spec.FilePath)
	if err != nil {
		return markdownUploadResult{}, common.WrapInputStatError(err)
	}
	defer f.Close()

	if fileSize > markdownSinglePartSizeLimit {
		return uploadMarkdownFileMultipart(runtime, spec, f, fileName, fileSize)
	}
	return uploadMarkdownFileAll(runtime, spec, f, fileName, fileSize)
}

func uploadMarkdownFileAll(runtime *common.RuntimeContext, spec markdownUploadSpec, fileReader io.Reader, fileName string, fileSize int64) (markdownUploadResult, error) {
	target := spec.Target()
	fd := larkcore.NewFormdata()
	fd.AddField("file_name", fileName)
	fd.AddField("parent_type", target.ParentType)
	fd.AddField("parent_node", target.ParentNode)
	fd.AddField("size", fmt.Sprintf("%d", fileSize))
	if spec.FileToken != "" {
		fd.AddField("file_token", spec.FileToken)
	}
	fd.AddFile("file", fileReader)

	apiResp, err := runtime.DoAPI(&larkcore.ApiReq{
		HttpMethod: http.MethodPost,
		ApiPath:    "/open-apis/drive/v1/files/upload_all",
		Body:       fd,
	}, larkcore.WithFileUpload())
	if err != nil {
		var exitErr *output.ExitError
		if errors.As(err, &exitErr) {
			return markdownUploadResult{}, err
		}
		return markdownUploadResult{}, output.ErrNetwork("upload failed: %v", err)
	}

	data, err := common.ParseDriveMediaUploadResponse(apiResp, "upload failed")
	if err != nil {
		return markdownUploadResult{}, err
	}
	return parseMarkdownUploadResult(data, spec.FileToken != "")
}

func uploadMarkdownFileMultipart(runtime *common.RuntimeContext, spec markdownUploadSpec, fileReader io.Reader, fileName string, fileSize int64) (markdownUploadResult, error) {
	target := spec.Target()
	prepareBody := map[string]interface{}{
		"file_name":   fileName,
		"parent_type": target.ParentType,
		"parent_node": target.ParentNode,
		"size":        fileSize,
	}
	if spec.FileToken != "" {
		prepareBody["file_token"] = spec.FileToken
	}

	prepareResult, err := runtime.CallAPI("POST", "/open-apis/drive/v1/files/upload_prepare", nil, prepareBody)
	if err != nil {
		return markdownUploadResult{}, err
	}

	session, err := parseMarkdownMultipartSession(prepareResult)
	if err != nil {
		return markdownUploadResult{}, err
	}

	fmt.Fprintf(runtime.IO().ErrOut, "Multipart upload initialized: %d chunks x %s\n", session.BlockNum, common.FormatSize(session.BlockSize))

	if err := uploadMarkdownMultipartParts(runtime, fileReader, fileSize, session); err != nil {
		return markdownUploadResult{}, err
	}

	finishResult, err := runtime.CallAPI("POST", "/open-apis/drive/v1/files/upload_finish", nil, map[string]interface{}{
		"upload_id": session.UploadID,
		"block_num": session.BlockNum,
	})
	if err != nil {
		return markdownUploadResult{}, err
	}

	return parseMarkdownUploadResult(finishResult, spec.FileToken != "")
}

func parseMarkdownMultipartSession(data map[string]interface{}) (markdownMultipartSession, error) {
	session := markdownMultipartSession{
		UploadID:  common.GetString(data, "upload_id"),
		BlockSize: int64(common.GetFloat(data, "block_size")),
		BlockNum:  int(common.GetFloat(data, "block_num")),
	}
	if session.UploadID == "" || session.BlockSize <= 0 || session.BlockNum <= 0 {
		return markdownMultipartSession{}, output.Errorf(output.ExitAPI, "api_error",
			"upload_prepare returned invalid data: upload_id=%q, block_size=%d, block_num=%d",
			session.UploadID, session.BlockSize, session.BlockNum)
	}
	return session, nil
}

func uploadMarkdownMultipartParts(runtime *common.RuntimeContext, fileReader io.Reader, payloadSize int64, session markdownMultipartSession) error {
	expectedBlocks := int((payloadSize + session.BlockSize - 1) / session.BlockSize)
	if session.BlockNum != expectedBlocks {
		return output.Errorf(
			output.ExitAPI,
			"api_error",
			"upload_prepare returned inconsistent chunk plan: block_size=%d, block_num=%d, expected_block_num=%d, payload_size=%d",
			session.BlockSize,
			session.BlockNum,
			expectedBlocks,
			payloadSize,
		)
	}

	maxInt := int64(^uint(0) >> 1)
	if session.BlockSize > maxInt {
		return output.Errorf(output.ExitAPI, "api_error", "upload prepare failed: invalid block_size returned")
	}

	buffer := make([]byte, int(session.BlockSize))
	remaining := payloadSize

	for seq := 0; seq < session.BlockNum; seq++ {
		chunkSize := session.BlockSize
		if remaining > 0 && chunkSize > remaining {
			chunkSize = remaining
		}

		n, readErr := io.ReadFull(fileReader, buffer[:int(chunkSize)])
		if readErr != nil {
			return output.ErrValidation("cannot read file: %s", readErr)
		}

		fd := larkcore.NewFormdata()
		fd.AddField("upload_id", session.UploadID)
		fd.AddField("seq", fmt.Sprintf("%d", seq))
		fd.AddField("size", fmt.Sprintf("%d", n))
		fd.AddFile("file", bytes.NewReader(buffer[:n]))

		apiResp, err := runtime.DoAPI(&larkcore.ApiReq{
			HttpMethod: http.MethodPost,
			ApiPath:    "/open-apis/drive/v1/files/upload_part",
			Body:       fd,
		}, larkcore.WithFileUpload())
		if err != nil {
			var exitErr *output.ExitError
			if errors.As(err, &exitErr) {
				return err
			}
			return output.ErrNetwork("upload part %d/%d failed: %v", seq+1, session.BlockNum, err)
		}

		if _, err := common.ParseDriveMediaUploadResponse(apiResp, fmt.Sprintf("upload part %d/%d failed", seq+1, session.BlockNum)); err != nil {
			return err
		}

		fmt.Fprintf(runtime.IO().ErrOut, "  Block %d/%d uploaded (%s)\n", seq+1, session.BlockNum, common.FormatSize(int64(n)))
		remaining -= int64(n)
	}
	if remaining != 0 {
		return output.Errorf(
			output.ExitAPI,
			"api_error",
			"upload_prepare returned inconsistent chunk plan: %d bytes remain after %d blocks",
			remaining,
			session.BlockNum,
		)
	}

	return nil
}

func parseMarkdownUploadResult(data map[string]interface{}, requireVersion bool) (markdownUploadResult, error) {
	result := markdownUploadResult{
		FileToken: common.GetString(data, "file_token"),
		Version:   common.GetString(data, "version"),
	}
	if result.Version == "" {
		result.Version = common.GetString(data, "data_version")
	}
	if result.FileToken == "" {
		return markdownUploadResult{}, output.Errorf(output.ExitAPI, "api_error", "upload failed: no file_token returned")
	}
	if requireVersion && result.Version == "" {
		return markdownUploadResult{}, output.Errorf(output.ExitAPI, "api_error", "overwrite failed: no version returned")
	}
	return result, nil
}

func fetchMarkdownFileName(runtime *common.RuntimeContext, fileToken string) (string, error) {
	data, err := runtime.CallAPI(
		"POST",
		"/open-apis/drive/v1/metas/batch_query",
		nil,
		map[string]interface{}{
			"request_docs": []map[string]interface{}{
				{
					"doc_token": fileToken,
					"doc_type":  "file",
				},
			},
		},
	)
	if err != nil {
		return "", err
	}

	metas := common.GetSlice(data, "metas")
	if len(metas) == 0 {
		return "", nil
	}
	meta, _ := metas[0].(map[string]interface{})
	return common.GetString(meta, "title"), nil
}

func prettyPrintMarkdownWrite(w io.Writer, data map[string]interface{}) {
	fmt.Fprintf(w, "file_token: %s\n", common.GetString(data, "file_token"))
	fmt.Fprintf(w, "file_name: %s\n", common.GetString(data, "file_name"))
	if url := common.GetString(data, "url"); url != "" {
		fmt.Fprintf(w, "url: %s\n", url)
	}
	version := common.GetString(data, "version")
	if version == "" {
		version = common.GetString(data, "data_version")
	}
	if version != "" {
		fmt.Fprintf(w, "version: %s\n", version)
	}
	fmt.Fprintf(w, "size_bytes: %d\n", int64(common.GetFloat(data, "size_bytes")))
	if grant := common.GetMap(data, "permission_grant"); grant != nil {
		fmt.Fprintf(w, "permission_grant.status: %s\n", common.GetString(grant, "status"))
		fmt.Fprintf(w, "permission_grant.perm: %s\n", common.GetString(grant, "perm"))
	}
}

func prettyPrintMarkdownSavedFile(w io.Writer, data map[string]interface{}) {
	fmt.Fprintf(w, "file_token: %s\n", common.GetString(data, "file_token"))
	fmt.Fprintf(w, "file_name: %s\n", common.GetString(data, "file_name"))
	fmt.Fprintf(w, "saved_path: %s\n", common.GetString(data, "saved_path"))
	fmt.Fprintf(w, "size_bytes: %d\n", int64(common.GetFloat(data, "size_bytes")))
}

func prettyPrintMarkdownContent(w io.Writer, data map[string]interface{}) {
	fmt.Fprint(w, common.GetString(data, "content"))
}

func fileNameFromDownloadHeader(header http.Header, fallback string) string {
	name := fallback
	if header != nil {
		if headerName := larkcore.FileNameByHeader(header); strings.TrimSpace(headerName) != "" {
			name = headerName
		}
	}
	name = strings.ReplaceAll(strings.TrimSpace(name), "\\", "/")
	name = path.Base(name)
	if name == "" || name == "." || name == ".." {
		return fallback
	}
	return name
}