package models

import (
	"database/sql"
	"regexp"
	"time"
)

type ChatMessage struct {
	ID        int           `json:"id"`
	UserID    int           `json:"userId"`
	Content   string        `json:"content"`
	ReplyTo   int           `json:"replyTo"`
	Timestamp time.Time     `json:"timestamp"`
	Username  string        `json:"username"`
	PfpFileID sql.NullInt64 `json:"pfpFileId"`
	Mentions  []string      `json:"mentions"`
}

func CreateChatMessage(db *sql.DB, msg ChatMessage) error {
	query := "INSERT INTO chat_messages (user_id, content, reply_to, timestamp) VALUES (?, ?, ?, NOW())"
	_, err := db.Exec(query, msg.UserID, msg.Content, msg.ReplyTo)
	return err
}

func GetRecentChatMessages(db *sql.DB, limit int) ([]ChatMessage, error) {
	query := `
		SELECT cm.id, cm.user_id, cm.content, cm.reply_to, cm.timestamp, u.username, u.pfp_file_id
		FROM chat_messages cm
		JOIN users u ON cm.user_id = u.id
		ORDER BY cm.timestamp DESC
		LIMIT ?`
	rows, err := db.Query(query, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var messages []ChatMessage
	for rows.Next() {
		var msg ChatMessage
		var timestampStr string
		err := rows.Scan(&msg.ID, &msg.UserID, &msg.Content, &msg.ReplyTo, &timestampStr, &msg.Username, &msg.PfpFileID)
		if err != nil {
			return nil, err
		}
		msg.Timestamp, err = time.Parse("2006-01-02 15:04:05", timestampStr)
		if err != nil {
			msg.Timestamp = time.Time{}
		}
		msg.Mentions = extractMentions(msg.Content)
		messages = append(messages, msg)
	}
	return messages, nil
}

func GetChatMessageByID(db *sql.DB, id int) (*ChatMessage, error) {
	query := `
		SELECT cm.id, cm.user_id, cm.content, cm.reply_to, cm.timestamp, u.username, u.pfp_file_id
		FROM chat_messages cm
		JOIN users u ON cm.user_id = u.id
		WHERE cm.id = ?`
	row := db.QueryRow(query, id)
	var msg ChatMessage
	var timestampStr string
	err := row.Scan(&msg.ID, &msg.UserID, &msg.Content, &msg.ReplyTo, &timestampStr, &msg.Username, &msg.PfpFileID)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	msg.Timestamp, err = time.Parse("2006-01-02 15:04:05", timestampStr)
	if err != nil {
		msg.Timestamp = time.Time{}
	}
	msg.Mentions = extractMentions(msg.Content)
	return &msg, nil
}

func GetUsernamesMatching(db *sql.DB, prefix string) ([]string, error) {
	query := "SELECT username FROM users WHERE username LIKE ? LIMIT 10"
	rows, err := db.Query(query, prefix+"%")
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var usernames []string
	for rows.Next() {
		var username string
		if err := rows.Scan(&username); err != nil {
			return nil, err
		}
		usernames = append(usernames, username)
	}
	return usernames, nil
}

// Simple utility to extract mentions from content
func extractMentions(content string) []string {
	re := regexp.MustCompile(`@(\w+)`)
	matches := re.FindAllStringSubmatch(content, -1)
	mentions := make([]string, len(matches))
	for i, match := range matches {
		mentions[i] = match[1]
	}
	return mentions
}