import type { CameraFrame } from './types'

type FrameListener = {
    start: () => void
    stop: () => void
}

type CameraContextLike = {
    onCameraFrame?: (cb: (frame: { width: number; height: number; data: ArrayBuffer }) => void) => FrameListener
}

function createContext(cameraId?: string): CameraContextLike | null {
    try {
        // uni-app 优先：可按 camera 组件 id 绑定
        if (typeof uni !== 'undefined' && typeof uni.createCameraContext === 'function') {
            return uni.createCameraContext(cameraId || 'gripCamera') as CameraContextLike
        }
    } catch (_) {}

    // #ifdef MP-WEIXIN
    try {
        // @ts-ignore
        if (typeof wx !== 'undefined' && typeof wx.createCameraContext === 'function') {
            // @ts-ignore
            return wx.createCameraContext() as CameraContextLike
        }
    } catch (_) {}
    // #endif
    return null
}

export function isCameraFrameSupported(): boolean {
    try {
        const ctx = createContext('gripCamera')
        return typeof ctx?.onCameraFrame === 'function'
    } catch (_) {
        return false
    }
}

/**
 * 管理 CameraContext.onCameraFrame：只保留最新一帧，不入 Vue 响应式。
 */
export function createCameraFramePump(options?: { cameraId?: string }) {
    let listener: FrameListener | null = null
    let latest: CameraFrame | null = null
    let running = false
    let callbackCount = 0
    let fpsWindowStart = Date.now()
    let fps = 0
    let onFrame: ((frame: CameraFrame) => void) | null = null

    function start(cb: (frame: CameraFrame) => void) {
        stop()
        onFrame = cb
        const ctx = createContext(options?.cameraId || 'gripCamera')
        if (!ctx?.onCameraFrame) {
            throw new Error('当前基础库不支持 onCameraFrame')
        }

        listener = ctx.onCameraFrame((raw) => {
            if (!running) return
            const frame: CameraFrame = {
                width: raw.width,
                height: raw.height,
                data: raw.data,
                ts: Date.now(),
            }
            latest = frame
            callbackCount += 1
            const now = Date.now()
            if (now - fpsWindowStart >= 1000) {
                fps = callbackCount
                callbackCount = 0
                fpsWindowStart = now
            }
            onFrame?.(frame)
        })
        running = true
        listener.start()
    }

    function stop() {
        running = false
        try {
            listener?.stop()
        } catch (_) {}
        listener = null
        onFrame = null
    }

    function getLatest() {
        return latest
    }

    function getFps() {
        return fps
    }

    function isRunning() {
        return running
    }

    return { start, stop, getLatest, getFps, isRunning }
}

export type CameraFramePump = ReturnType<typeof createCameraFramePump>