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

package cmdpolicy

import (
	"sync"

	"github.com/larksuite/cli/extension/platform"
)

// ActivePolicy is the resolved user-layer policy after applyUserPolicyPruning
// has run during bootstrap. `lark-cli config policy show` reads this to
// answer "what rule is currently in effect, and how many commands does
// it hide?".
//
// Set once at bootstrap time; consumed read-only thereafter.
//
// Rules is the full set the winning source contributed (one rule for the
// common single-rule case, several when a plugin or yaml declares scoped
// grants). nil/empty means "no rule applied".
type ActivePolicy struct {
	Rules       []*platform.Rule
	Source      ResolveSource
	DeniedPaths int // number of commands the engine marked as denied (post-aggregation)
}

var (
	activeMu     sync.RWMutex
	activePolicy *ActivePolicy
)

// SetActive records the policy that ends up applied. Called exactly once
// per process from cmd/policy.go::applyUserPolicyPruning. The mutex is
// belt-and-braces in case future test paths interleave with bootstrap.
//
// A deep copy is taken so the snapshot is immune to later mutations of
// the input by the caller (a plugin-supplied *Rule could otherwise
// mutate the embedded Allow/Deny/Identities slices after we stored it).
func SetActive(p *ActivePolicy) {
	activeMu.Lock()
	defer activeMu.Unlock()
	if p == nil {
		activePolicy = nil
		return
	}
	activePolicy = cloneActivePolicy(p)
}

// GetActive returns a deep copy of the recorded policy, or nil if
// bootstrap has not finished or no rule applied. Callers can freely
// mutate the result — including the embedded Rule slices — without
// affecting the stored global.
func GetActive() *ActivePolicy {
	activeMu.RLock()
	defer activeMu.RUnlock()
	if activePolicy == nil {
		return nil
	}
	return cloneActivePolicy(activePolicy)
}

// cloneActivePolicy deep-copies the top-level struct, the Rules slice, and
// each Rule's own slice fields. Other fields (Source, DeniedPaths) are
// value types so the struct copy already disjoints them.
func cloneActivePolicy(in *ActivePolicy) *ActivePolicy {
	if in == nil {
		return nil
	}
	cp := *in
	if in.Rules != nil {
		cp.Rules = make([]*platform.Rule, len(in.Rules))
		for i, r := range in.Rules {
			if r == nil {
				continue
			}
			rule := *r
			rule.Allow = append([]string(nil), r.Allow...)
			rule.Deny = append([]string(nil), r.Deny...)
			rule.Identities = append([]platform.Identity(nil), r.Identities...)
			cp.Rules[i] = &rule
		}
	}
	return &cp
}

// ResetActiveForTesting clears the recorded policy. Tests must call this
// in t.Cleanup when they exercise the bootstrap path.
func ResetActiveForTesting() {
	activeMu.Lock()
	defer activeMu.Unlock()
	activePolicy = nil
}