package rules

import (
	"context"
	"log"
	"time"

	"gitea.wayfinderak.com/wayfinderak/log-guardian/internal/actions"
	"gitea.wayfinderak.com/wayfinderak/log-guardian/internal/alerts"
	"gitea.wayfinderak.com/wayfinderak/log-guardian/internal/analysis"
	"gitea.wayfinderak.com/wayfinderak/log-guardian/internal/loki"
	"gitea.wayfinderak.com/wayfinderak/log-guardian/internal/store"
)

type Store interface {
	Load() (store.Data, error)
	UpdateRule(id string, fn func(*store.Rule)) error
	AddIncident(incident store.Incident) error
}

type Engine struct {
	store      Store
	loki       *loki.Client
	analyzer   analysis.Analyzer
	actions    *actions.Runner
	dispatcher *alerts.Dispatcher
}

func NewEngine(s Store, lokiClient *loki.Client, analyzer analysis.Analyzer, actionRunner *actions.Runner, dispatcher *alerts.Dispatcher) *Engine {
	return &Engine{store: s, loki: lokiClient, analyzer: analyzer, actions: actionRunner, dispatcher: dispatcher}
}

func (e *Engine) Start(ctx context.Context, interval time.Duration) {
	if interval <= 0 {
		interval = time.Minute
	}
	ticker := time.NewTicker(interval)
	defer ticker.Stop()
	for {
		e.CheckAll(ctx)
		select {
		case <-ctx.Done():
			return
		case <-ticker.C:
		}
	}
}

func (e *Engine) CheckAll(ctx context.Context) {
	data, err := e.store.Load()
	if err != nil {
		log.Printf("load rules failed: %v", err)
		return
	}
	channels := map[string]store.AlertChannel{}
	for _, channel := range data.AlertChannels {
		channels[channel.ID] = channel
	}
	for _, rule := range data.Rules {
		if !rule.Enabled {
			continue
		}
		if err := e.checkRule(ctx, rule, channels); err != nil {
			log.Printf("rule %q check failed: %v", rule.Name, err)
		}
	}
}

func (e *Engine) checkRule(ctx context.Context, rule store.Rule, channels map[string]store.AlertChannel) error {
	window, err := time.ParseDuration(rule.Window)
	if err != nil {
		window = 5 * time.Minute
	}
	result, err := e.loki.QueryRange(ctx, rule.LogQL, window, 200)
	if err != nil {
		e.record(rule.ID, 0, err)
		return err
	}
	if result.Count < rule.Threshold {
		return e.record(rule.ID, result.Count, nil)
	}
	now := time.Now().UTC()
	cooldown, err := time.ParseDuration(rule.Cooldown)
	if err != nil || cooldown <= 0 {
		cooldown = time.Hour
	}
	if !rule.LastAlertedAt.IsZero() && now.Sub(rule.LastAlertedAt) < cooldown {
		return e.store.UpdateRule(rule.ID, func(r *store.Rule) {
			r.LastCheckedAt = now
			r.LastMatchedAt = now
			r.LastMatchCount = result.Count
			r.SuppressedCount++
			r.LastError = ""
		})
	}
	finding, err := e.analyzer.Analyze(ctx, rule, result.Matches)
	if err != nil {
		e.record(rule.ID, result.Count, err)
		return err
	}
	selected := make([]store.AlertChannel, 0, len(rule.AlertChannels))
	for _, id := range rule.AlertChannels {
		if channel, ok := channels[id]; ok {
			selected = append(selected, channel)
		}
	}
	alertResults, alertErr := e.dispatcher.Send(ctx, rule, finding, selected)
	var alertEvidence []string
	for _, result := range alertResults {
		if result.ChannelID == "" {
			alertEvidence = append(alertEvidence, result.Detail)
		} else {
			alertEvidence = append(alertEvidence, result.ChannelID+": "+result.Detail)
		}
	}
	var actionEvidence []string
	for _, action := range rule.Actions {
		result, err := e.actions.Run(ctx, rule, action)
		if err != nil {
			log.Printf("action %q for rule %q failed: %v", action.Type, rule.Name, err)
			actionEvidence = append(actionEvidence, action.Type+": "+err.Error())
			continue
		}
		actionEvidence = append(actionEvidence, result.Action+": "+result.Detail)
	}
	incident := store.Incident{RuleID: rule.ID, RuleName: rule.Name, Severity: rule.Severity, Count: result.Count, Summary: finding.Summary, AlertResults: alertEvidence, RemediationEvidence: actionEvidence, CreatedAt: now}
	if err := e.store.AddIncident(incident); err != nil {
		return err
	}
	if err := e.store.UpdateRule(rule.ID, func(r *store.Rule) {
		r.LastCheckedAt = now
		r.LastMatchedAt = now
		r.LastAlertedAt = now
		r.LastMatchCount = result.Count
		r.LastError = ""
	}); err != nil {
		return err
	}
	return alertErr
}

func (e *Engine) record(id string, count int, err error) error {
	return e.store.UpdateRule(id, func(r *store.Rule) {
		r.LastCheckedAt = time.Now().UTC()
		r.LastMatchCount = count
		if err != nil {
			r.LastError = err.Error()
		} else {
			r.LastError = ""
		}
	})
}