import { DatabaseInterface, UploadTask } from './types';

export class SQLiteDatabase implements DatabaseInterface {
    private db: any;

    constructor() {
        // 动态导入，避免在Web环境下加载
        try {
            const SQLite = require('expo-sqlite');
            this.db = SQLite.openDatabaseSync('upload_status.db');
            this.db.execSync('PRAGMA busy_timeout = 5000;');
        } catch (error) {
            console.error('Failed to initialize SQLite:', error);
            throw new Error('SQLite is not available in this environment');
        }
    }

    async initUploadTable(): Promise<void> {
        console.log('Initializing upload tasks table...');
        await this.db.execAsync(`
            CREATE TABLE IF NOT EXISTS upload_tasks (
                uri TEXT PRIMARY KEY NOT NULL,
                filename TEXT NOT NULL,
                status TEXT NOT NULL DEFAULT 'pending',
                progress INTEGER NOT NULL DEFAULT 0,
                file_id TEXT,
                created_at INTEGER NOT NULL DEFAULT (strftime('%s', 'now'))
            );
        `);

        // Add created_at column to existing table if it doesn't exist
        const columns = await this.db.getAllAsync('PRAGMA table_info(upload_tasks);');
        const columnExists = columns.some((column: any) => column.name === 'created_at');

        if (!columnExists) {
            console.log('Adding created_at column to upload_tasks table...');
            await this.db.execAsync(`ALTER TABLE upload_tasks ADD COLUMN created_at INTEGER;`);
            await this.db.execAsync(`UPDATE upload_tasks SET created_at = (strftime('%s', 'now')) WHERE created_at IS NULL;`);
            console.log('created_at column added and populated.');
        }
        console.log('Upload tasks table initialized');

        await this.db.execAsync(`
            CREATE TABLE IF NOT EXISTS app_state (
                key TEXT PRIMARY KEY NOT NULL,
                value TEXT
            );
        `);
        console.log('App state table initialized');
    }

    async insertUploadTask(task: Omit<UploadTask, 'created_at'>): Promise<void> {
        console.log('Inserting upload task:', task.uri);
        await this.db.runAsync(
            'INSERT OR REPLACE INTO upload_tasks (uri, filename, status, progress, file_id, created_at) VALUES (?, ?, ?, ?, ?, ?)',
            [task.uri, task.filename, task.status, task.progress, task.file_id ?? null, Math.floor(Date.now() / 1000)]
        );
    }

    async getUploadTaskStatus(uri: string): Promise<UploadTask | null> {
        console.log('Checking upload task status for:', uri);
        const result = await this.db.getFirstAsync(
            'SELECT uri, filename, status, progress, file_id, created_at FROM upload_tasks WHERE uri = ?;',
            uri
        );
        return result || null;
    }

    async updateUploadTaskStatus(uri: string, status: UploadTask['status'], file_id?: string): Promise<void> {
        if (file_id) {
            await this.db.runAsync('UPDATE upload_tasks SET status = ?, file_id = ? WHERE uri = ?', [status, file_id, uri]);
        } else {
            await this.db.runAsync('UPDATE upload_tasks SET status = ? WHERE uri = ?', [status, uri]);
        }
    }

    async updateUploadTaskProgress(uri: string, progress: number): Promise<void> {
        await this.db.runAsync('UPDATE upload_tasks SET progress = ? WHERE uri = ?', [progress, uri]);
    }

    async getUploadTasks(): Promise<UploadTask[]> {
        console.log('Fetching all upload tasks... time:', new Date().toLocaleString());
        const results = await this.db.getAllAsync(
            'SELECT uri, filename, status, progress, file_id, created_at FROM upload_tasks ORDER BY created_at DESC;'
        );
        return results;
    }

    async cleanUpUploadTasks(): Promise<void> {
        console.log('Cleaning up completed/failed upload tasks...');
        await this.db.runAsync(
            "DELETE FROM upload_tasks WHERE status = 'success' OR status = 'failed' OR status = 'skipped';"
        );
    }

    async getUploadTasksSince(timestamp: number): Promise<UploadTask[]> {
        const rows = await this.db.getAllAsync(
            'SELECT * FROM upload_tasks WHERE created_at >= ? ORDER BY created_at DESC',
            [timestamp]
        );
        return rows;
    }

    async exist_pending_tasks(): Promise<boolean> {
        const rows = await this.db.getAllAsync(
            'SELECT * FROM upload_tasks WHERE status = "pending" OR status = "uploading"'
        );
        return rows.length > 0;
    }

    async filterExistingFiles(fileUris: string[]): Promise<string[]> {
        if (fileUris.length === 0) {
            return [];
        }

        const placeholders = fileUris.map(() => '?').join(',');
        const query = `SELECT uri FROM upload_tasks WHERE uri IN (${placeholders}) AND status = 'success'`;

        const existingFiles = await this.db.getAllAsync(query, fileUris);
        const existingUris = new Set(existingFiles.map((f: { uri: string }) => f.uri));
        const newFileUris = fileUris.filter(uri => !existingUris.has(uri));

        console.log(`[DB] Total files: ${fileUris.length}, Existing successful files: ${existingUris.size}, New files to upload: ${newFileUris.length}`);

        return newFileUris;
    }

    async setAppState(key: string, value: string | null): Promise<void> {
        console.log(`Setting app state: ${key} = ${value}`);
        await this.db.runAsync('INSERT OR REPLACE INTO app_state (key, value) VALUES (?, ?)', [key, value]);
    }

    async getAppState(key: string): Promise<string | null> {
        const result = await this.db.getFirstAsync('SELECT value FROM app_state WHERE key = ?;', key);
        return result?.value ?? null;
    }

    async executeSql(sql: string, params: any[] = []): Promise<any> {
        try {
            const isSelect = sql.trim().toLowerCase().startsWith('select');
            if (isSelect) {
                const results = this.db.getAllSync(sql, params);
                return results;
            } else {
                const result = this.db.runSync(sql, params);
                return {
                    changes: result.changes,
                    lastInsertRowId: result.lastInsertRowId,
                };
            }
        } catch (error: any) {
            console.error("Error executing SQL:", error);
            return { error: error.message };
        }
    }
}