package engine

import (
	"context"
	"fmt"
	"git.yeij.top/AskaEth/Cyrene_v2/internal/logger"
	"sync"
	"time"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/plugin"
)

// Rule is an automation rule. Trigger types: "time" (cron), "event" (device state).
// The action is a natural-language instruction executed through the AI pipeline,
// so it can call any tool (IoT control, search, etc.).
type Rule struct {
	ID        string
	Name      string
	Trigger   string            // "time" | "event" | "webhook"
	Condition map[string]string // time: {"cron": "..."}; event: {"device_id","field","value"}
	Action    string
	Enabled   bool
}

// RuleSource provides the current automation rules.
type RuleSource interface {
	List() []Rule
}

// AIFunc executes an action prompt through the AI pipeline (fire and forget).
type AIFunc func(ctx context.Context, sessionID, userID, message string)

// DeviceQuerier polls IoT device states for event triggers.
type DeviceQuerier interface {
	ListDevices(ctx context.Context) ([]plugin.Device, error)
}

// Engine evaluates automation rules on a ticker.
type Engine struct {
	src      RuleSource
	ai       AIFunc
	devices  DeviceQuerier
	interval time.Duration

	mu            sync.Mutex
	lastCronFire  map[string]string // ruleID → fired minute key
	deviceMatches map[string]bool   // ruleID → condition held last poll
	stop          chan struct{}
	stopOnce      sync.Once
}

// New creates an automation engine.
func New(src RuleSource, ai AIFunc, devices DeviceQuerier, interval time.Duration) *Engine {
	if interval <= 0 {
		interval = 30 * time.Second
	}
	return &Engine{
		src:           src,
		ai:            ai,
		devices:       devices,
		interval:      interval,
		lastCronFire:  map[string]string{},
		deviceMatches: map[string]bool{},
		stop:          make(chan struct{}),
	}
}

// Start begins the evaluation loop.
func (e *Engine) Start(ctx context.Context) {
	go func() {
		ticker := time.NewTicker(e.interval)
		defer ticker.Stop()
		for {
			select {
			case <-e.stop:
				return
			case <-ctx.Done():
				return
			case t := <-ticker.C:
				e.check(ctx, t)
			}
		}
	}()
	logger.Infof("[automation] engine started (interval=%v)", e.interval)
}

// Stop shuts down the engine.
func (e *Engine) Stop() { e.stopOnce.Do(func() { close(e.stop) }) }

// Trigger fires a rule immediately (manual / webhook).
func (e *Engine) Trigger(ctx context.Context, id string) error {
	for _, r := range e.src.List() {
		if r.ID == id {
			e.fire(ctx, r, "manual")
			return nil
		}
	}
	return fmt.Errorf("rule %s not found", id)
}

// check evaluates all rules once.
func (e *Engine) check(ctx context.Context, now time.Time) {
	for _, r := range e.src.List() {
		if !r.Enabled {
			continue
		}
		switch r.Trigger {
		case "time":
			e.checkCron(ctx, r, now)
		case "event":
			e.checkDevice(ctx, r)
		}
	}
}

func (e *Engine) checkCron(ctx context.Context, r Rule, now time.Time) {
	expr := r.Condition["cron"]
	if expr == "" {
		return
	}
	sched, err := ParseCron(expr)
	if err != nil {
		return
	}
	if !sched.Match(now) {
		return
	}
	// Fire at most once per minute per rule
	minuteKey := now.Format("2006-01-02 15:04")
	e.mu.Lock()
	if e.lastCronFire[r.ID] == minuteKey {
		e.mu.Unlock()
		return
	}
	e.lastCronFire[r.ID] = minuteKey
	e.mu.Unlock()
	e.fire(ctx, r, "cron")
}

func (e *Engine) checkDevice(ctx context.Context, r Rule) {
	if e.devices == nil {
		return
	}
	devID, field, want := r.Condition["device_id"], r.Condition["field"], r.Condition["value"]
	if devID == "" || field == "" {
		return
	}

	devices, err := e.devices.ListDevices(ctx)
	if err != nil {
		return
	}
	held := false
	for _, d := range devices {
		if d.ID != devID {
			continue
		}
		if v, ok := d.State[field]; ok && fmt.Sprint(v) == want {
			held = true
		}
	}

	// Edge trigger: only fire when the condition starts holding
	e.mu.Lock()
	was := e.deviceMatches[r.ID]
	e.deviceMatches[r.ID] = held
	e.mu.Unlock()
	if held && !was {
		e.fire(ctx, r, "device_state")
	}
}

func (e *Engine) fire(ctx context.Context, r Rule, reason string) {
	logger.Infof("[automation] rule %q fired (%s): %s", r.Name, reason, r.Action)
	if e.ai != nil && r.Action != "" {
		go e.ai(ctx, "automation-"+r.ID, "automation", r.Action)
	}
}