package intentflow

import (
	"fmt"
	"os"
	"strings"
	"sync"

	"chat-agent-system/internal/intent"
)

// PlanTier is the intentflow rollout switch. It must not be stored on
// intent.ActionSpec or intent.FeatureFlags.
type PlanTier string

const (
	TierLegacy   PlanTier = "legacy"
	TierShadow   PlanTier = "shadow"
	TierAutoRead PlanTier = "auto_read"
	TierConfirm  PlanTier = "confirm"
	TierFull     PlanTier = "full"
)

type FeatureFlags struct {
	PlanTier PlanTier
	// ProjectAllowlist gates elevated tiers (shadow/auto_read/confirm/full).
	// Empty denies; AllowAllProjects (-1) allows every project.
	// Env: INTENT_PLAN_PROJECT_ALLOWLIST (*|id,id,...)
	ProjectAllowlist []int64
	// Independent PU8 expansion gates. Default OFF; do not couple to PlanTier.
	U9Segment     bool // MULTI_INTENT_U9_SEGMENT — LLM segment proposal
	U10Mutate     bool // MULTI_INTENT_U10_MUTATE — low/medium mutate adapters
	U11DocGov     bool // MULTI_INTENT_U11_DOCGOV — docgov action adapters
	U12RunControl bool // MULTI_INTENT_U12_RUN_CONTROL — workflow/run-control adapters
	// 逐键 live 放量 flag（P8）：域名总 flag 开启后，细粒度键仍须单独打开才走真实引擎；
	// 未打开的键保持 validated_only dry-run。默认全 OFF，禁止 full 一次放量。
	U11LiveReview   bool // MULTI_INTENT_U11_LIVE_REVIEW — document.review.approve/reject
	U11LiveFinal    bool // MULTI_INTENT_U11_LIVE_FINAL — document.final.approve/reject
	U11LiveProposal bool // MULTI_INTENT_U11_LIVE_PROPOSAL — document.proposal.decide
	U12LiveSwitch   bool // MULTI_INTENT_U12_LIVE_SWITCH — workflow.switch
	U12LiveRestart  bool // MULTI_INTENT_U12_LIVE_RESTART — run.restart
}

var (
	flagsMu     sync.RWMutex
	activeFlags = defaultFeatureFlags()
)

func defaultFeatureFlags() FeatureFlags {
	return FeatureFlags{
		PlanTier:         parsePlanTier(os.Getenv("MULTI_INTENT_PLAN_TIER")),
		ProjectAllowlist: ParseProjectAllowlist(os.Getenv("INTENT_PLAN_PROJECT_ALLOWLIST")),
		U9Segment:        envBool("MULTI_INTENT_U9_SEGMENT", false),
		U10Mutate:        envBool("MULTI_INTENT_U10_MUTATE", false),
		U11DocGov:        envBool("MULTI_INTENT_U11_DOCGOV", false),
		U12RunControl:    envBool("MULTI_INTENT_U12_RUN_CONTROL", false),
		U11LiveReview:    envBool("MULTI_INTENT_U11_LIVE_REVIEW", false),
		U11LiveFinal:     envBool("MULTI_INTENT_U11_LIVE_FINAL", false),
		U11LiveProposal:  envBool("MULTI_INTENT_U11_LIVE_PROPOSAL", false),
		U12LiveSwitch:    envBool("MULTI_INTENT_U12_LIVE_SWITCH", false),
		U12LiveRestart:   envBool("MULTI_INTENT_U12_LIVE_RESTART", false),
	}
}

func envBool(key string, def bool) bool {
	v := strings.TrimSpace(os.Getenv(key))
	if v == "" {
		return def
	}
	return v == "1" || strings.EqualFold(v, "true") || strings.EqualFold(v, "yes")
}

func parsePlanTier(raw string) PlanTier {
	switch strings.ToLower(strings.TrimSpace(raw)) {
	case "", "legacy":
		return TierLegacy
	case "shadow":
		return TierShadow
	case "auto_read", "autoread":
		return TierAutoRead
	case "confirm":
		return TierConfirm
	case "full":
		return TierFull
	default:
		return TierLegacy
	}
}

func CurrentFeatureFlags() FeatureFlags {
	flagsMu.RLock()
	defer flagsMu.RUnlock()
	return activeFlags
}

func SetFeatureFlagsForTest(f FeatureFlags) {
	flagsMu.Lock()
	activeFlags = f
	flagsMu.Unlock()
}

func ResetFeatureFlagsForTest() {
	flagsMu.Lock()
	activeFlags = defaultFeatureFlags()
	flagsMu.Unlock()
}

// Allows reports whether the current (or supplied) tier may activate a policy row.
func (t PlanTier) Allows(min PlanTier) bool {
	return tierRank(t) >= tierRank(min)
}

func tierRank(t PlanTier) int {
	switch t {
	case TierLegacy:
		return 0
	case TierShadow:
		return 1
	case TierAutoRead:
		return 2
	case TierConfirm:
		return 3
	case TierFull:
		return 4
	default:
		return 0
	}
}

// ValidateFlagConsistency 校验 intentflow 放量档位与 intent 多意图开关的
// 一致性（FIND-QUAL-01 回归）：PlanTier 升档必须建立在 MULTI_INTENT_ENABLED
// 之上，否则组合根启动期 fail-fast，不允许「intentflow 已升档、intent 仍关」
// 这类静默漂移配置上线。
func ValidateFlagConsistency(iflags intent.FeatureFlags, pflags FeatureFlags) error {
	if pflags.PlanTier != TierLegacy && !iflags.MultiIntentEnabled {
		return fmt.Errorf(
			"intentflow: MULTI_INTENT_PLAN_TIER=%q requires MULTI_INTENT_ENABLED=true; fix the flag combination instead of silently degrading",
			pflags.PlanTier,
		)
	}
	return nil
}