/** 头像等媒体：真机选图后须 saveFile，/static/ 须 getImageInfo */

function buildStaticPathCandidates(url) {
    const list = [url]
    if (url.startsWith('/')) {
        list.push(url.slice(1))
    } else {
        list.push(`/${url}`)
    }
    return [...new Set(list.filter(Boolean))]
}

function isPackageStaticPath(url) {
    return /^(\/)?static\//i.test(url)
}

/** chooseImage / saveFile 产生的本地路径（含真机 temp、usr、store） */
export function isLocalFilePath(url) {
    if (!url) return false
    if (/^(wxfile:|file:|blob:|data:)/i.test(url)) return true
    if (/^https?:\/\/(tmp|usr|store)\//i.test(url)) return true
    if (/^https?:\/\//i.test(url) && !isPackageStaticPath(url)) return true
    return false
}

function showPreviewFail() {
    uni.showToast({ title: '无法预览头像', icon: 'none' })
}

function openPreview(path, onFail) {
    if (!path) {
        ;(onFail || showPreviewFail)()
        return
    }
    uni.previewImage({
        urls: [path],
        current: path,
        fail: () => (onFail ? onFail() : showPreviewFail())
    })
}

function previewLocalFile(url) {
    openPreview(url, () => {
        uni.getImageInfo({
            src: url,
            success: (res) => {
                openPreview(res.path || url, showPreviewFail)
            },
            fail: showPreviewFail
        })
    })
}

function tryGetImageInfo(candidates, index, onSuccess, onFail) {
    if (index >= candidates.length) {
        onFail()
        return
    }
    uni.getImageInfo({
        src: candidates[index],
        success: (res) => onSuccess(res.path || candidates[index]),
        fail: () => tryGetImageInfo(candidates, index + 1, onSuccess, onFail)
    })
}

function getMpUserDataPath() {
    // #ifdef MP-WEIXIN
    return wx.env.USER_DATA_PATH
    // #endif
    return ''
}

function tryCopyFile(candidates, index, onSuccess, onFail) {
    // #ifdef MP-WEIXIN
    const userPath = getMpUserDataPath()
    if (!userPath) {
        onFail()
        return
    }
    const fs = uni.getFileSystemManager()
    const extMatch = candidates[0]?.match(/\.(\w+)(?:\?|$)/)
    const ext = extMatch ? extMatch[1] : 'png'
    const dest = `${userPath}/avatar_preview_${Date.now()}.${ext}`

    if (index >= candidates.length) {
        onFail()
        return
    }

    fs.copyFile({
        srcPath: candidates[index],
        destPath: dest,
        success: () => onSuccess(dest),
        fail: () => tryCopyFile(candidates, index + 1, onSuccess, onFail)
    })
    // #endif
    // #ifndef MP-WEIXIN
    onFail()
    // #endif
}

function previewPackageStatic(url) {
    const candidates = buildStaticPathCandidates(url)
    tryGetImageInfo(
        candidates,
        0,
        (path) => openPreview(path, showPreviewFail),
        () => {
            tryCopyFile(
                candidates,
                0,
                (path) => openPreview(path, showPreviewFail),
                showPreviewFail
            )
        }
    )
}

/** 选图后将临时文件转为真机可预览、可持久化的本地路径 */
export function persistChosenImage(tempPath) {
    return new Promise((resolve) => {
        const path = String(tempPath || '').trim()
        if (!path) {
            resolve('')
            return
        }

        // #ifdef MP-WEIXIN
        uni.saveFile({
            tempFilePath: path,
            success: (res) => resolve(res.savedFilePath || path),
            fail: () => resolve(path)
        })
        // #endif
        // #ifndef MP-WEIXIN
        resolve(path)
        // #endif
    })
}

export function previewImage(src, fallback = '') {
    const url = String(src || fallback || '').trim()
    if (!url) {
        uni.showToast({ title: '暂无头像', icon: 'none' })
        return
    }

    if (isLocalFilePath(url)) {
        previewLocalFile(url)
        return
    }

    if (isPackageStaticPath(url)) {
        previewPackageStatic(url)
        return
    }

    previewLocalFile(url)
}