package bot

import (
	"context"
	"database/sql"
	"encoding/json"
	"log/slog"
	"sync"

	"git.dustin.coffee/hobokenchicken/dumpsterChat/internal/gateway"
)

// BotFunc is the signature for a built-in bot type's run function.
// It blocks until ctx is cancelled. Use send to post messages, db to read.
type BotFunc func(ctx context.Context, db *sql.DB, config json.RawMessage, send SendMessageFunc)

// SendMessageFunc posts a message to a channel as this bot.
type SendMessageFunc func(channelID, content string)

// Runner manages server-side bot goroutines.
type Runner struct {
	db     *sql.DB
	hub    *gateway.Hub
	logger *slog.Logger

	mu      sync.Mutex
	bots    map[string]context.CancelFunc // botID -> cancel
	types   map[string]BotFunc            // type name -> runner
}

func NewRunner(db *sql.DB, hub *gateway.Hub, logger *slog.Logger) *Runner {
	return &Runner{
		db:    db,
		hub:   hub,
		logger: logger,
		bots:  make(map[string]context.CancelFunc),
		types: make(map[string]BotFunc),
	}
}

// Register adds a built-in bot type.
func (r *Runner) Register(name string, fn BotFunc) {
	r.types[name] = fn
}

// StartAll loads all bots with a bot_type set and starts them.
func (r *Runner) StartAll() {
	rows, err := r.db.QueryContext(context.Background(),
		`SELECT id, bot_type, config::text FROM bots WHERE bot_type != ''`)
	if err != nil {
		r.logger.Error("failed to load bot configs", "error", err)
		return
	}
	defer rows.Close()

	for rows.Next() {
		var id, botType, configStr string
		if err := rows.Scan(&id, &botType, &configStr); err != nil {
			continue
		}
		r.Start(id, botType, json.RawMessage(configStr))
	}
}

// Start starts a single bot by ID. Safe to call multiple times (restarts).
func (r *Runner) Start(botID, botType string, config json.RawMessage) {
	r.mu.Lock()
	// Stop existing if running
	if cancel, ok := r.bots[botID]; ok {
		cancel()
		delete(r.bots, botID)
	}

	fn, ok := r.types[botType]
	if !ok {
		r.mu.Unlock()
		r.logger.Warn("unknown bot type", "type", botType, "bot_id", botID)
		return
	}

	ctx, cancel := context.WithCancel(context.Background())
	r.bots[botID] = cancel
	r.mu.Unlock()

	// Built-in bots pick a channel in config but users often skip "Add to Server".
	// Resolve channel_id → server and ensure bot_servers so send() doesn't no-op.
	r.ensureBotServerFromConfig(botID, config)

	send := r.makeSender(botID)
	r.logger.Info("starting built-in bot", "bot_id", botID, "type", botType)

	go func() {
		defer func() {
			if rec := recover(); rec != nil {
				r.logger.Error("bot panic", "bot_id", botID, "type", botType, "panic", rec)
			}
		}()
		fn(ctx, r.db, config, send)
		r.logger.Info("bot stopped", "bot_id", botID, "type", botType)
	}()
}

// ensureBotServerFromConfig joins the bot to the server that owns config.channel_id.
func (r *Runner) ensureBotServerFromConfig(botID string, config json.RawMessage) {
	var cfg struct {
		ChannelID string `json:"channel_id"`
	}
	if err := json.Unmarshal(config, &cfg); err != nil || cfg.ChannelID == "" {
		return
	}
	serverID, err := r.hub.ServerIDForChannel(context.Background(), cfg.ChannelID)
	if err != nil || serverID == "" {
		r.logger.Warn("bot start: channel not found for auto-join", "bot_id", botID, "channel_id", cfg.ChannelID, "error", err)
		return
	}
	var ownerID string
	if err := r.db.QueryRowContext(context.Background(),
		`SELECT owner_id FROM bots WHERE id = $1`, botID,
	).Scan(&ownerID); err != nil {
		return
	}
	if _, err := r.db.ExecContext(context.Background(), `
		INSERT INTO bot_servers (bot_id, server_id, added_by)
		VALUES ($1, $2, $3)
		ON CONFLICT DO NOTHING
	`, botID, serverID, ownerID); err != nil {
		r.logger.Warn("bot start: auto-join server failed", "bot_id", botID, "server_id", serverID, "error", err)
		return
	}
	r.logger.Info("bot auto-joined server", "bot_id", botID, "server_id", serverID)
}

// Stop stops a single bot by ID.
func (r *Runner) Stop(botID string) {
	r.mu.Lock()
	defer r.mu.Unlock()
	if cancel, ok := r.bots[botID]; ok {
		cancel()
		delete(r.bots, botID)
	}
}

// IsRunning checks if a bot is currently running.
func (r *Runner) IsRunning(botID string) bool {
	r.mu.Lock()
	defer r.mu.Unlock()
	_, ok := r.bots[botID]
	return ok
}

// makeSender returns a SendMessageFunc that inserts into DB and broadcasts.
func (r *Runner) makeSender(botID string) SendMessageFunc {
	return func(channelID, content string) {
		if len(content) > 4000 {
			content = content[:4000]
		}

		// Look up bot info + server
		var botName, ownerID string
		err := r.db.QueryRowContext(context.Background(),
			`SELECT name, owner_id FROM bots WHERE id = $1`, botID,
		).Scan(&botName, &ownerID)
		if err != nil {
			r.logger.Error("send: bot not found", "bot_id", botID, "error", err)
			return
		}

		serverID, err := r.hub.ServerIDForChannel(context.Background(), channelID)
		if err != nil {
			r.logger.Error("send: channel not found", "channel_id", channelID, "error", err)
			return
		}

		// Verify bot is in this server
		var inServer bool
		err = r.db.QueryRowContext(context.Background(),
			`SELECT EXISTS(SELECT 1 FROM bot_servers WHERE bot_id = $1 AND server_id = $2)`,
			botID, serverID,
		).Scan(&inServer)
		if err != nil || !inServer {
			r.logger.Warn("send: bot not in server", "bot_id", botID, "server_id", serverID)
			return
		}

		var msgID, createdAt string
		err = r.db.QueryRowContext(context.Background(),
			`INSERT INTO messages (channel_id, author_id, content, bot_id)
			 VALUES ($1, $2, $3, $4)
			 RETURNING id, created_at::text`,
			channelID, ownerID, content, botID,
		).Scan(&msgID, &createdAt)
		if err != nil {
			r.logger.Error("send: insert failed", "error", err)
			return
		}

		r.hub.BroadcastToServer(serverID, gateway.Event{
			Type: gateway.EventMessageCreate,
			Data: map[string]interface{}{
				"id":                  msgID,
				"channel_id":          channelID,
				"author_id":           ownerID,
				"author_username":     botName,
				"author_display_name": nil,
				"author_bot":          true,
				"bot_id":              botID,
				"bot_name":            botName,
				"content":             content,
				"reply_to":            nil,
				"edited_at":           nil,
				"pinned":              false,
				"created_at":          createdAt,
				"embeds":              []interface{}{},
				"reactions":           []interface{}{},
			},
		})
	}
}

// RegisteredTypes returns the list of available bot type names.
func (r *Runner) RegisteredTypes() []string {
	r.mu.Lock()
	defer r.mu.Unlock()
	names := make([]string, 0, len(r.types))
	for k := range r.types {
		names = append(names, k)
	}
	return names
}