import type { SnapshotScheduleType } from "@core/db/schema.d.ts";
import logger from "@core/log/logger.ts";
import { MINUTE } from "@core/const/time.ts";
import { redis } from "@core/db/redis.ts";
import { Redis } from "ioredis";
import { parseTimestampFromPsql } from "../utils/formatTimestampToPostgre.ts";
import type { Psql } from "@core/db/psql.d.ts";

const REDIS_KEY = "cvsa:snapshot_window_counts";

function getCurrentWindowIndex(): number {
	const now = new Date();
	const minutesSinceMidnight = now.getHours() * 60 + now.getMinutes();
	return Math.floor(minutesSinceMidnight / 5);
}

export async function refreshSnapshotWindowCounts(sql: Psql, redisClient: Redis) {
	const now = new Date();
	const startTime = now.getTime();

	const result = await sql<{ window_start: Date; count: number }[]>`
		SELECT 
		date_trunc('hour', started_at) + 
		(EXTRACT(minute FROM started_at)::int / 5 * INTERVAL '5 minutes') AS window_start,
		COUNT(*) AS count
		FROM snapshot_schedule
		WHERE started_at >= NOW() AND status = 'pending' AND started_at <= NOW() + INTERVAL '10 days'
		GROUP BY 1
		ORDER BY window_start
  	`;

	await redisClient.del(REDIS_KEY);

	const currentWindow = getCurrentWindowIndex();

	for (const row of result) {
		const targetOffset = Math.floor((row.window_start.getTime() - startTime) / (5 * MINUTE));
		const offset = currentWindow + targetOffset;
		if (offset >= 0) {
			await redisClient.hset(REDIS_KEY, offset.toString(), Number(row.count));
		}
	}
}

export async function initSnapshotWindowCounts(sql: Psql, redisClient: Redis) {
	await refreshSnapshotWindowCounts(sql, redisClient);
	setInterval(async () => {
		await refreshSnapshotWindowCounts(sql, redisClient);
	}, 5 * MINUTE);
}

async function getWindowCount(redisClient: Redis, offset: number): Promise<number> {
	const count = await redisClient.hget(REDIS_KEY, offset.toString());
	return count ? parseInt(count, 10) : 0;
}

export async function snapshotScheduleExists(sql: Psql, id: number) {
	const rows = await sql<{ id: number }[]>`
		SELECT id 
		FROM snapshot_schedule 
		WHERE id = ${id}
	`;
	return rows.length > 0;
}

export async function videoHasActiveSchedule(sql: Psql, aid: number) {
	const rows = await sql<{ status: string }[]>`
		SELECT status
		FROM snapshot_schedule 
		WHERE aid = ${aid}
			AND (status = 'pending' 
				OR status = 'processing'
			)
	`
	return rows.length > 0;
}

export async function videoHasActiveScheduleWithType(sql: Psql, aid: number, type: string) {
	const rows = await sql<{ status: string }[]>`
		SELECT status FROM snapshot_schedule 
		WHERE aid = ${aid}
			AND (status = 'pending' OR status = 'processing') 
			AND type = ${type}
	`;
	return rows.length > 0;
}

export async function videoHasProcessingSchedule(sql: Psql, aid: number) {
	const rows = await sql<{ status: string }[]>`
		SELECT status
		FROM snapshot_schedule 
		WHERE aid = ${aid}
			AND status = 'processing'
	`
	return rows.length > 0;
}

export async function bulkGetVideosWithoutProcessingSchedules(sql: Psql, aids: number[]) {
	const rows = await sql<{ aid: string }[]>`
		SELECT aid
		FROM snapshot_schedule
		WHERE aid = ANY(${aids})
			AND status != 'processing' 
		GROUP BY aid
	`
	return rows.map((row) => Number(row.aid));
}

interface Snapshot {
	created_at: number;
	views: number;
}

export async function findClosestSnapshot(sql: Psql, aid: number, targetTime: Date): Promise<Snapshot | null> {
	const result = await sql<{ created_at: string; views: number }[]>`
        SELECT created_at, views
        FROM video_snapshot
        WHERE aid = ${aid}
        ORDER BY ABS(EXTRACT(EPOCH FROM (created_at - ${targetTime.toISOString()}::timestamptz)))
        LIMIT 1
	`;
	if (result.length === 0) return null;
	const row = result[0];
	return {
		created_at: new Date(row.created_at).getTime(),
		views: row.views
	};
}

export async function findSnapshotBefore(sql: Psql, aid: number, targetTime: Date): Promise<Snapshot | null> {
	const result = await sql<{ created_at: string; views: number }[]>`
        SELECT created_at, views
        FROM video_snapshot
        WHERE aid = ${aid}
		AND created_at <= ${targetTime}::timestamptz
        ORDER BY created_at DESC
        LIMIT 1
	`;
	if (result.length === 0) return null;
	const row = result[0];
	return {
		created_at: new Date(row.created_at).getTime(),
		views: row.views
	};
}

export async function hasAtLeast2Snapshots(sql: Psql, aid: number) {
	const res = await sql<{ count: number }[]>`
		SELECT COUNT(*) 
		FROM video_snapshot 
		WHERE aid = ${aid}
	`;
	return res[0].count >= 2;
}

export async function getLatestSnapshot(sql: Psql, aid: number): Promise<Snapshot | null> {
	const res = await sql<{ created_at: string; views: number }[]>`
		SELECT created_at, views 
		FROM video_snapshot 
		WHERE aid = ${aid}
		ORDER BY created_at DESC 
		LIMIT 1
	`;
	if (res.length === 0) return null;
	const row = res[0];
	return {
		created_at: new Date(row.created_at).getTime(),
		views: row.views
	};
}

export async function getLatestActiveScheduleWithType(sql: Psql, aid: number, type: string) {
	const rows = await sql`
		SELECT *
		FROM snapshot_schedule
		WHERE aid = ${aid}
		  AND type = ${type}
		  AND (status = 'pending' OR status = 'processing')
		ORDER BY started_at DESC
		LIMIT 1
	`;
	return rows[0];
}

/*
 * Creates a new snapshot schedule record.
 * @param aid The aid of the video.
 * @param type Type of the snapshot.
 * @param targetTime Scheduled time for snapshot. (Timestamp in milliseconds)
 * @param force Ignore all restrictions and force the creation of the schedule.
 */
export async function scheduleSnapshot(
	sql: Psql,
	aid: number,
	type: string,
	targetTime: number,
	force: boolean = false
) {
	let adjustedTime = new Date(targetTime);
	const hashActiveSchedule = await videoHasActiveScheduleWithType(sql, aid, type);
	if (type == "milestone" && hashActiveSchedule) {
		const latestActiveSchedule = await getLatestActiveScheduleWithType(sql, aid, type);
		const latestScheduleStartedAt = new Date(parseTimestampFromPsql(latestActiveSchedule.started_at!));
		if (latestScheduleStartedAt > adjustedTime) {
			await sql`
                UPDATE snapshot_schedule
                SET started_at = ${adjustedTime}
                WHERE id = ${latestActiveSchedule.id}
			`;
			logger.log(
				`Updated snapshot schedule for ${aid} at ${adjustedTime.toISOString()}`,
				"mq",
				"fn:scheduleSnapshot"
			);
			return;
		}
	}
	if (hashActiveSchedule && !force) return;
	if (type !== "milestone" && type !== "new") {
		adjustedTime = await adjustSnapshotTime(new Date(targetTime), 2000, redis);
	}
	logger.log(`Scheduled snapshot for ${aid} at ${adjustedTime.toISOString()}`, "mq", "fn:scheduleSnapshot");
	return sql`
		INSERT INTO snapshot_schedule 
			(aid, type, started_at) 
			VALUES (
				${aid}, 
				${type}, 
				${adjustedTime.toISOString()}
			)
	`;
}

export async function bulkScheduleSnapshot(
	sql: Psql,
	aids: number[],
	type: string,
	targetTime: number,
	force: boolean = false
) {
	for (const aid of aids) {
		await scheduleSnapshot(sql, aid, type, targetTime, force);
	}
}

export async function adjustSnapshotTime(
	expectedStartTime: Date,
	allowedCounts: number = 1000,
	redisClient: Redis
): Promise<Date> {
	const currentWindow = getCurrentWindowIndex();
	const targetOffset = Math.floor((expectedStartTime.getTime() - Date.now()) / (5 * MINUTE)) - 6;

	const initialOffset = currentWindow + Math.max(targetOffset, 0);

	let timePerIteration: number;
	const MAX_ITERATIONS = 2880;
	let iters = 0;
	const t = performance.now();
	for (let i = initialOffset; i < MAX_ITERATIONS; i++) {
		iters++;
		const offset = i;
		const count = await getWindowCount(redisClient, offset);

		if (count < allowedCounts) {
			await redisClient.hincrby(REDIS_KEY, offset.toString(), 1);

			const startPoint = new Date();
			startPoint.setHours(0, 0, 0, 0);
			const startTime = startPoint.getTime();
			const windowStart = startTime + offset * 5 * MINUTE;
			const randomDelay = Math.floor(Math.random() * 5 * MINUTE);
			const delayedDate = new Date(windowStart + randomDelay);
			const now = new Date();

			if (delayedDate.getTime() < now.getTime()) {
				const elapsed = performance.now() - t;
				timePerIteration = elapsed / (i + 1);
				logger.log(`${timePerIteration.toFixed(3)}ms * ${iters} iterations`, "perf", "fn:adjustSnapshotTime");
				return now;
			}
			const elapsed = performance.now() - t;
			timePerIteration = elapsed / (i + 1);
			logger.log(`${timePerIteration.toFixed(3)}ms * ${iters} iterations`, "perf", "fn:adjustSnapshotTime");
			return delayedDate;
		}
	}
	const elapsed = performance.now() - t;
	timePerIteration = elapsed / MAX_ITERATIONS;
	logger.log(`${timePerIteration.toFixed(3)}ms * ${MAX_ITERATIONS} iterations`, "perf", "fn:adjustSnapshotTime");
	return expectedStartTime;
}

export async function getSnapshotsInNextSecond(sql: Psql) {
	const rows = await sql<SnapshotScheduleType[]>`
		SELECT *
		FROM snapshot_schedule
		WHERE started_at <= NOW() + INTERVAL '1 seconds' AND status = 'pending' AND type != 'normal'
		ORDER BY
			CASE
				WHEN type = 'milestone' THEN 0
				ELSE 1
			END,
			started_at
		LIMIT 10;
	`
	return rows;
}

export async function getBulkSnapshotsInNextSecond(sql: Psql) {
	const rows = await sql<SnapshotScheduleType[]>`
        SELECT *
        FROM snapshot_schedule
        WHERE (started_at <= NOW() + INTERVAL '15 seconds')
          AND status = 'pending'
          AND (type = 'normal' OR type = 'archive')
        ORDER BY CASE
                     WHEN type = 'normal' THEN 1
                     WHEN type = 'archive' THEN 2
                     END,
                 started_at
        LIMIT 1000;
	`
	return rows;
}

export async function setSnapshotStatus(sql: Psql, id: number, status: string) {
	return await sql`
		UPDATE snapshot_schedule SET status = ${status} WHERE id = ${id}
	`;
}

export async function bulkSetSnapshotStatus(sql: Psql, ids: number[], status: string) {
	return await sql`
		UPDATE snapshot_schedule SET status = ${status} WHERE id = ANY(${ids})
	`;
}

export async function getVideosWithoutActiveSnapshotSchedule(sql: Psql) {
	const rows = await sql<{ aid: string }[]>`
		SELECT s.aid
		FROM songs s
		LEFT JOIN snapshot_schedule ss ON s.aid = ss.aid AND (ss.status = 'pending' OR ss.status = 'processing')
		WHERE ss.aid IS NULL
	`;
	return rows.map((r) => Number(r.aid));
}

export async function getAllVideosWithoutActiveSnapshotSchedule(psql: Psql) {
	const rows = await psql<{ aid: number }[]>`
		SELECT s.aid
		FROM bilibili_metadata s
		LEFT JOIN snapshot_schedule ss ON s.aid = ss.aid AND (ss.status = 'pending' OR ss.status = 'processing')
		WHERE ss.aid IS NULL
	`
	return rows.map((r) => Number(r.aid));
}