package bot

import (
	"context"
	"database/sql"
	"encoding/json"
	"fmt"
	"strings"
	"time"
)

// ConfessConfig: "channel_id" is where anonymous confessions land.
type ConfessConfig struct {
	ChannelID string `json:"channel_id"`
}

// ConfessBot watches for /confess messages, deletes the original, reposts anonymously.
func ConfessBot(ctx context.Context, db *sql.DB, raw json.RawMessage, send SendMessageFunc) {
	var cfg ConfessConfig
	if err := json.Unmarshal(raw, &cfg); err != nil || cfg.ChannelID == "" {
		return
	}

	// Cursor is (created_at, id) in memory so deletes don't break polling.
	var lastAt time.Time
	var lastID string
	seeded := false

	ticker := time.NewTicker(10 * time.Second)
	defer ticker.Stop()

	for {
		select {
		case <-ctx.Done():
			return
		case <-ticker.C:
			confessPoll(db, cfg.ChannelID, &seeded, &lastAt, &lastID, send)
		}
	}
}

func confessPoll(db *sql.DB, targetChannel string, seeded *bool, lastAt *time.Time, lastID *string, send SendMessageFunc) {
	if !*seeded {
		var at sql.NullTime
		var id sql.NullString
		_ = db.QueryRowContext(context.Background(),
			`SELECT created_at, id::text FROM messages ORDER BY created_at DESC, id DESC LIMIT 1`,
		).Scan(&at, &id)
		if at.Valid {
			*lastAt = at.Time
		}
		if id.Valid {
			*lastID = id.String
		}
		*seeded = true
		return
	}

	rows, err := db.QueryContext(context.Background(), `
		SELECT m.id::text, m.created_at, m.content
		FROM messages m
		WHERE m.bot_id IS NULL
		  AND lower(m.content) LIKE '/confess%'
		  AND (m.created_at, m.id) > ($1::timestamptz, $2::uuid)
		ORDER BY m.created_at ASC, m.id ASC
		LIMIT 20
	`, *lastAt, nullUUID(*lastID))
	if err != nil {
		return
	}
	defer rows.Close()

	for rows.Next() {
		var id string
		var createdAt time.Time
		var content string
		if err := rows.Scan(&id, &createdAt, &content); err != nil {
			continue
		}
		*lastAt = createdAt
		*lastID = id

		rest := content
		if len(rest) >= 8 && strings.EqualFold(rest[:8], "/confess") {
			rest = rest[8:]
		}
		text := strings.TrimSpace(rest)
		if text == "" {
			continue
		}

		// Delete original so author isn't exposed in chat history.
		_, _ = db.ExecContext(context.Background(), `DELETE FROM messages WHERE id = $1::uuid`, id)
		send(targetChannel, fmt.Sprintf("🕵️ **anonymous confession:** %s", text))
	}
}

// nullUUID returns a zero UUID when empty so the first post-seed poll still works.
func nullUUID(id string) string {
	if id == "" {
		return "00000000-0000-0000-0000-000000000000"
	}
	return id
}