import Foundation
import UIKit
import SwiftData

/// VL 解析结果(已结构化,可直接喂 SwiftData 模型构造)。
/// 与 Indicator/Report 字段近似但解耦 —— 这样 prompt schema 调整不污染数据层。
struct ParsedReport: Sendable {
    var title: String
    var typeRaw: String
    var reportDate: Date
    var institution: String
    var summary: String
    var pageCount: Int
    var indicators: [ParsedIndicator]

    struct ParsedIndicator: Sendable, Identifiable {
        // 稳定身份:供可编辑列表 ForEach 用,避免按 indices 作 id 在增删时错配输入。
        let id = UUID()
        var name: String
        var value: String
        var unit: String
        var range: String
        var status: IndicatorStatus
        var sourcePageIndex: Int?
        var sourceBoxX: Double?
        var sourceBoxY: Double?
        var sourceBoxWidth: Double?
        var sourceBoxHeight: Double?
    }

    /// 一项都没识别出来 = 视作失败,UI 走手动录入回退。
    var isEmpty: Bool { indicators.isEmpty }

    /// 占位空结果,失败回退时给 UI。
    static func empty(date: Date = .now) -> ParsedReport {
        ParsedReport(
            title: "",
            typeRaw: ReportType.other.rawValue,
            reportDate: date,
            institution: "",
            summary: "",
            pageCount: 1,
            indicators: []
        )
    }
}

/// CaptureService 错误 — UI 决定怎么呈现(回退表单 vs 重试)。
enum CaptureError: Error, LocalizedError {
    case modelNotReady
    case inferenceFailed(String)
    case parseFailed(String)

    var errorDescription: String? {
        switch self {
        case .modelNotReady:           return String(appLoc: "VL 模型尚未就绪")
        case .inferenceFailed(let m):  return String(appLoc: "识别失败:\(m)")
        case .parseFailed(let m):      return String(appLoc: "结构化失败:\(m)")
        }
    }
}

/// `CaptureService` 是 actor 是因为它的方法会等 AIRuntime(也是 actor),
/// 但本身不持任何可变状态 —— 单例 stateless,纯粹是 §3.1 模块边界的"门面"。
actor CaptureService {
    static let shared = CaptureService()
    private init() {}

    /// 对已写入 Vault 的 Asset 跑 VL,返回结构化 ParsedReport。
    /// 用于:
    /// - UnifiedCaptureFlow 的初次识别(UI 先写图、再调本方法,失败/取消都能保留 assets 走手动录入)
    /// - 录入表单顶部的「重新识别」按钮
    /// - C2「重新解读」(W5)
    /// SwiftData 写回由调用方(MainActor)负责,见 `Report.applyReanalyzed(_:in:)`。
    /// 不直接接 @Model 类型,避免把非 Sendable 引用抛过 actor 边界。
    func reanalyze(assets: [FileVault.SavedAsset]) async throws -> ParsedReport {
        try await runVL(on: assets)
    }

    /// 「拍照识别」OCR 链路:把 Vision OCR 出的纯文本交给 LLM(Qwen3-1.7B)结构化抽指标。
    /// 不建 Report、不留图;失败抛 `CaptureError`,UI 回退手动录入(§3.2)。
    /// 调用方(MainActor)先做 OCR,再把文本传进来——OCR 不需进 actor,也避免 UIImage 跨 actor。
    func recognizeIndicators(fromOCRText text: String) async throws -> [ParsedReport.ParsedIndicator] {
        do {
            try await AIRuntime.shared.prepare()   // 载 LLM(会先卸 VL,OOM 闸门已处理)
        } catch {
            throw CaptureError.modelNotReady
        }

        let prompt = VLPrompts.indicatorsFromText(text)
        var collected = ""
        do {
            // 整张化验单十余项,给足 token;LLM 解码与任何 VL 解码由 AIRuntime 闸门串行。
            let stream = await AIRuntime.shared.generate(prompt: prompt, maxTokens: 2048)
            for try await chunk in stream {
                collected += chunk.text
            }
        } catch {
            throw CaptureError.inferenceFailed("\(error)")
        }

        // Qwen3 可能吐 <think>…</think>,先剥掉再抠 JSON。
        let cleaned = CaptureService.stripThink(collected)
        #if DEBUG
        // 取证:原始输出(含可能未闭合的 <think>)+ strip 后,定位「空/非法 JSON」根因。
        // 用 NSLog(走统一日志)而非 print(stdout 被 Xcode lldb 接管,idevicesyslog 抓不到)。
        NSLog("KKDBG-VL RAW LLM output (%d chars):\n%@\n--- end RAW ---", collected.count, collected)
        NSLog("KKDBG-VL cleaned (%d chars):\n%@\n--- end cleaned ---", cleaned.count, cleaned)
        #endif
        do {
            return try CaptureService.parseIndicatorsJSON(cleaned)
        } catch let CaptureError.parseFailed(msg) {
            // 把模型实际输出的特征带到屏幕上,便于现场定位(原始长度 / strip 后长度 / 前缀)。
            let rawLen = collected.count
            let cleanLen = cleaned.count
            let preview = cleaned.isEmpty ? "(strip 后为空)" : String(cleaned.prefix(60))
            throw CaptureError.parseFailed("\(msg)〔raw \(rawLen)字/clean \(cleanLen)字·前缀:\(preview)〕")
        } catch {
            throw CaptureError.parseFailed("\(error)")
        }
    }

    /// 剥掉 Qwen3 的 <think>…</think>(配对块 / 未闭合开标签 / 孤立闭标签),再 trim 顶部空白。
    /// 与 HealthExportService.stripThinkBlocks 同逻辑,但本类是非 MainActor actor,放一份 nonisolated 版避免跨隔离调用。
    nonisolated static func stripThink(_ raw: String) -> String {
        var s = raw
        while let openR = s.range(of: "<think>"),
              let closeR = s.range(of: "</think>", range: openR.upperBound..<s.endIndex) {
            s.removeSubrange(openR.lowerBound..<closeR.upperBound)
        }
        if let openR = s.range(of: "<think>") { s = String(s[..<openR.lowerBound]) }
        if let closeR = s.range(of: "</think>") { s = String(s[closeR.upperBound...]) }
        while let first = s.first, first.isWhitespace { s.removeFirst() }
        return s
    }

    /// VL 推理 + JSON 解析的纯阶段。assets 必须已写入 Vault。
    private func runVL(on assets: [FileVault.SavedAsset]) async throws -> ParsedReport {
        do {
            try await AIRuntime.shared.prepareVL()
        } catch {
            throw CaptureError.modelNotReady
        }
        let urls = assets.map { FileVault.shared.rootURL.appendingPathComponent($0.relativePath) }
        let raw: String
        do {
            raw = try await AIRuntime.shared.analyzeReport(
                imageURLs: urls,
                prompt: VLPrompts.reportExtraction()
            )
        } catch {
            throw CaptureError.inferenceFailed("\(error)")
        }
        do {
            return try CaptureService.parseReportJSON(raw, pageCount: assets.count)
        } catch let CaptureError.parseFailed(msg) {
            throw CaptureError.parseFailed(msg)
        } catch {
            throw CaptureError.parseFailed("\(error)")
        }
    }

    // MARK: - JSON parse(static + 纯函数 → 方便单测)

    /// 从 VL 输出里抠出第一段合法 JSON 对象并解析。
    /// 容错:
    /// - 去掉 ```json``` markdown 围栏
    /// - 去掉首尾非 JSON 文字
    /// - 缺字段填默认值
    /// 解析不到任何 indicator 也算成功,但 ParsedReport.isEmpty = true,
    /// UI 走「手动录入」分支。
    static func parseReportJSON(_ raw: String, pageCount: Int = 1) throws -> ParsedReport {
        // 用 extractBalancedJSON(而非只认 {} 的 extractJSONObject):VL 多项时偶尔直接吐
        // 裸数组 [{...},{...}],只认对象会从第一个 { 配对,只截出第一个 indicator、静默丢掉
        // 其余 —— 这是影像档案核心卖点上的数据丢失。顶层是数组时整体视作 indicators。
        let jsonString = repairJSON(extractBalancedJSON(from: raw))
        guard let data = jsonString.data(using: .utf8) else {
            throw CaptureError.parseFailed("非 UTF-8 输出")
        }
        let obj: Any
        do {
            obj = try JSONSerialization.jsonObject(with: data, options: [.fragmentsAllowed])
        } catch {
            throw CaptureError.parseFailed("JSON 不合法:\(error.localizedDescription)")
        }
        let dict: [String: Any]
        if let d = obj as? [String: Any] {
            dict = d
        } else if let arr = obj as? [[String: Any]] {
            dict = ["indicators": arr]
        } else {
            throw CaptureError.parseFailed("根节点既不是对象也不是数组")
        }

        let title = (dict["title"] as? String)?.trimmingCharacters(in: .whitespaces) ?? ""
        let typeRaw = parseReportType(dict["type"] as? String)
        let reportDate = parseDate(dict["report_date"] as? String) ?? .now
        let institution = (dict["institution"] as? String) ?? ""
        let summary = (dict["summary"] as? String) ?? ""
        let pages = (dict["page_count"] as? Int) ?? pageCount

        let indicatorsRaw = arrayValue(dict, keys: ["indicators", "indicator", "items", "指标", "指标列表", "项目"])
        let indicators: [ParsedReport.ParsedIndicator] = indicatorsRaw.compactMap {
            parseIndicator($0)
        }

        return ParsedReport(
            title: title.isEmpty ? String(appLoc: "拍摄识别") : title,
            typeRaw: typeRaw,
            reportDate: reportDate,
            institution: institution,
            summary: summary,
            pageCount: max(pages, pageCount),
            indicators: indicators
        )
    }

    /// 局部识别解析:VL 输出 `{"indicators":[...]}`,只抠 indicators 数组。
    /// 复用 `extractJSONObject` + `parseIndicator`。解析不到任何 indicator 返回空数组(不抛),
    /// UI 据此走「没读出指标,手动补充」分支。JSON 本身不合法才抛 `parseFailed`。
    static func parseIndicatorsJSON(_ raw: String) throws -> [ParsedReport.ParsedIndicator] {
        let jsonString = repairJSON(extractBalancedJSON(from: raw))
        guard let data = jsonString.data(using: .utf8) else {
            throw CaptureError.parseFailed("非 UTF-8 输出")
        }
        let obj: Any
        do {
            obj = try JSONSerialization.jsonObject(with: data, options: [.fragmentsAllowed])
        } catch {
            throw CaptureError.parseFailed("JSON 不合法:\(error.localizedDescription)")
        }
        // 兼容两种形态:{"indicators":[...]} 或直接 [...](模型偶尔省外层 key)
        let indicatorsRaw: [[String: Any]]
        if let dict = obj as? [String: Any] {
            indicatorsRaw = arrayValue(dict, keys: ["indicators", "indicator", "items", "指标", "指标列表", "项目"])
        } else if let arr = obj as? [[String: Any]] {
            indicatorsRaw = arr
        } else {
            throw CaptureError.parseFailed("根节点既不是对象也不是数组")
        }
        return indicatorsRaw.compactMap { parseIndicator($0) }
    }

    /// 从字符串里抠出第一段平衡的 {...}。处理 markdown 围栏、前后乱码。
    /// 失败返回原字符串(后续 JSONSerialization 报错)。
    static func extractJSONObject(from raw: String) -> String {
        var s = raw.trimmingCharacters(in: .whitespacesAndNewlines)

        // 去 markdown 围栏
        if s.hasPrefix("```") {
            // 砍掉首行 ```json 或 ```
            if let firstNewline = s.firstIndex(of: "\n") {
                s = String(s[s.index(after: firstNewline)...])
            }
            // 砍掉末尾 ```
            if let endRange = s.range(of: "```", options: .backwards) {
                s = String(s[..<endRange.lowerBound])
            }
            s = s.trimmingCharacters(in: .whitespacesAndNewlines)
        }

        // 找第一个 {,然后括号配对到匹配的 }
        guard let start = s.firstIndex(of: "{") else { return s }
        var depth = 0
        var inString = false
        var escape = false
        var idx = start
        while idx < s.endIndex {
            let ch = s[idx]
            if escape { escape = false }
            else if ch == "\\" { escape = true }
            else if ch == "\"" { inString.toggle() }
            else if !inString {
                if ch == "{" { depth += 1 }
                else if ch == "}" {
                    depth -= 1
                    if depth == 0 {
                        return String(s[start...idx])
                    }
                }
            }
            idx = s.index(after: idx)
        }
        return String(s[start...])
    }

    /// 弱模型(2B)常见 JSON 畸形的安全修复,仅在 JSONSerialization 前兜底:
    /// - 中文弯引号 “ ” → 直引号 "(模型偶尔给 key/value 套全角引号)
    /// - 去对象/数组尾逗号(`,}` / `,]` → `}` / `]`)
    /// 修不好仍按原逻辑报错;只做结构性修正,不改字符串语义。
    static func repairJSON(_ s: String) -> String {
        var t = s
        t = t.replacingOccurrences(of: "\u{201C}", with: "\"")  // “
        t = t.replacingOccurrences(of: "\u{201D}", with: "\"")  // ”
        if let re = try? NSRegularExpression(pattern: ",\\s*([}\\]])") {
            t = re.stringByReplacingMatches(
                in: t, range: NSRange(t.startIndex..., in: t), withTemplate: "$1")
        }
        return t
    }

    /// 抠出第一段平衡的 JSON 值,`{...}` 或 `[...]` 以先出现者为准。
    /// 用于局部识别(模型可能输出 `{"indicators":[...]}` 或裸 `[...]`)。
    /// 失败返回去围栏后的原串(后续 JSONSerialization 报错)。
    static func extractBalancedJSON(from raw: String) -> String {
        var s = raw.trimmingCharacters(in: .whitespacesAndNewlines)
        if s.hasPrefix("```") {
            if let firstNewline = s.firstIndex(of: "\n") {
                s = String(s[s.index(after: firstNewline)...])
            }
            if let endRange = s.range(of: "```", options: .backwards) {
                s = String(s[..<endRange.lowerBound])
            }
            s = s.trimmingCharacters(in: .whitespacesAndNewlines)
        }

        let firstBrace = s.firstIndex(of: "{")
        let firstBracket = s.firstIndex(of: "[")
        let start: String.Index
        let open: Character
        let close: Character
        switch (firstBrace, firstBracket) {
        case let (b?, k?):
            if b < k { start = b; open = "{"; close = "}" }
            else     { start = k; open = "["; close = "]" }
        case let (b?, nil): start = b; open = "{"; close = "}"
        case let (nil, k?): start = k; open = "["; close = "]"
        default: return s
        }

        var depth = 0
        var inString = false
        var escape = false
        var idx = start
        while idx < s.endIndex {
            let ch = s[idx]
            if escape { escape = false }
            else if ch == "\\" { escape = true }
            else if ch == "\"" { inString.toggle() }
            else if !inString {
                if ch == open { depth += 1 }
                else if ch == close {
                    depth -= 1
                    if depth == 0 { return String(s[start...idx]) }
                }
            }
            idx = s.index(after: idx)
        }
        return String(s[start...])
    }

    private static func parseReportType(_ raw: String?) -> String {
        guard let raw = raw?.lowercased() else { return ReportType.other.rawValue }
        return ReportType(rawValue: raw)?.rawValue ?? ReportType.other.rawValue
    }

    private static func parseDate(_ raw: String?) -> Date? {
        guard let s = raw?.trimmingCharacters(in: .whitespaces), !s.isEmpty else { return nil }
        let f = DateFormatter()
        f.locale = Locale(identifier: "en_US_POSIX")
        // VL 不同来源会吐多种日期格式;逐一尝试,避免解析失败回退到「今天」(parseReportJSON 里
        // ?? .now)导致归档按 reportDate 分年份时错位(C1)。
        let patterns = ["yyyy-MM-dd", "yyyy/MM/dd", "yyyy.MM.dd",
                        "yyyy年MM月dd日", "yyyy年M月d日", "yyyy年MM月", "yyyy-MM", "yyyy/MM"]
        for p in patterns {
            f.dateFormat = p
            if let d = f.date(from: s) { return d }
        }
        return nil
    }

    private static func parseIndicator(_ d: [String: Any]) -> ParsedReport.ParsedIndicator? {
        guard let name = stringValue(d, keys: ["name", "item", "indicator", "test", "项目", "指标", "指标名", "指标名称", "检查项目", "检验项目"])?.trimmingCharacters(in: .whitespaces),
              !name.isEmpty else { return nil }
        let value: String
        if let v = stringValue(d, keys: ["value", "result", "reading", "结果", "数值", "检测值", "测定值"]) { value = v }
        else { value = "" }
        let unit = stringValue(d, keys: ["unit", "单位"]) ?? ""
        let range = stringValue(d, keys: ["range", "reference", "reference_range", "ref", "参考", "参考值", "参考范围", "正常范围"]) ?? ""
        let statusRaw = stringValue(d, keys: ["status", "flag", "abnormal", "异常", "提示", "标记"])
        let status = parseIndicatorStatus(raw: statusRaw, value: value, range: range)
        let evidence = parseEvidenceLocation(d)
        return .init(
            name: name,
            value: value,
            unit: unit,
            range: range,
            status: status,
            sourcePageIndex: evidence?.pageIndex,
            sourceBoxX: evidence?.box.x,
            sourceBoxY: evidence?.box.y,
            sourceBoxWidth: evidence?.box.width,
            sourceBoxHeight: evidence?.box.height
        )
    }

    private static func parseEvidenceLocation(_ d: [String: Any]) -> (pageIndex: Int, box: (x: Double, y: Double, width: Double, height: Double))? {
        guard let page = intValue(d, keys: ["source_page", "sourcePage", "page", "页码", "来源页码"]),
              page >= 1,
              let box = numberArrayValue(d, keys: ["source_box", "sourceBox", "box", "bbox", "位置", "来源位置"]),
              box.count == 4 else {
            return nil
        }
        let x = box[0]
        let y = box[1]
        let width = box[2]
        let height = box[3]
        guard x >= 0, y >= 0, width > 0, height > 0, x + width <= 1, y + height <= 1 else {
            return nil
        }
        return (page - 1, (x, y, width, height))
    }

    private static func stringValue(_ d: [String: Any], keys: [String]) -> String? {
        for key in keys {
            if let s = d[key] as? String {
                return s
            }
            if let n = d[key] as? NSNumber {
                return n.stringValue
            }
        }
        return nil
    }

    private static func intValue(_ d: [String: Any], keys: [String]) -> Int? {
        for key in keys {
            if let i = d[key] as? Int {
                return i
            }
            if let n = d[key] as? NSNumber {
                return n.intValue
            }
            if let s = d[key] as? String, let i = Int(s.trimmingCharacters(in: .whitespacesAndNewlines)) {
                return i
            }
        }
        return nil
    }

    private static func numberArrayValue(_ d: [String: Any], keys: [String]) -> [Double]? {
        for key in keys {
            if let arr = d[key] as? [Double] {
                return arr
            }
            if let arr = d[key] as? [NSNumber] {
                return arr.map(\.doubleValue)
            }
            if let arr = d[key] as? [Any] {
                let values = arr.compactMap { item -> Double? in
                    if let d = item as? Double { return d }
                    if let n = item as? NSNumber { return n.doubleValue }
                    if let s = item as? String { return Double(s.trimmingCharacters(in: .whitespacesAndNewlines)) }
                    return nil
                }
                if values.count == arr.count {
                    return values
                }
            }
        }
        return nil
    }

    private static func arrayValue(_ d: [String: Any], keys: [String]) -> [[String: Any]] {
        for key in keys {
            if let arr = d[key] as? [[String: Any]] {
                return arr
            }
        }
        return []
    }

    private static func parseIndicatorStatus(raw: String?, value: String, range: String) -> IndicatorStatus {
        let normalized = raw?
            .trimmingCharacters(in: .whitespacesAndNewlines)
            .lowercased() ?? ""

        if ["high", "h", "hi", "above", "up", "↑", "⬆", "+", "偏高", "高", "增高", "升高", "偏高↑", "h↑"].contains(normalized) {
            return .high
        }
        if ["low", "l", "lo", "below", "down", "↓", "⬇", "-", "偏低", "低", "降低", "偏低↓", "l↓"].contains(normalized) {
            return .low
        }
        if ["normal", "n", "ok", "正常", "阴性", "无异常"].contains(normalized) {
            return .normal
        }

        return inferStatus(value: value, range: range) ?? .normal
    }

    private static func inferStatus(value: String, range: String) -> IndicatorStatus? {
        guard let v = firstNumber(in: value) else { return nil }
        let compact = range
            .replacingOccurrences(of: "—", with: "-")
            .replacingOccurrences(of: "–", with: "-")
            .replacingOccurrences(of: "～", with: "-")
            .replacingOccurrences(of: "~", with: "-")
            .replacingOccurrences(of: "至", with: "-")
            .trimmingCharacters(in: .whitespacesAndNewlines)
        guard !compact.isEmpty else { return nil }

        let numbers = numbers(in: compact)
        if compact.contains("<") || compact.contains("≤") || compact.contains("＜") {
            guard let upper = numbers.first else { return nil }
            return v > upper ? .high : .normal
        }
        if compact.contains(">") || compact.contains("≥") || compact.contains("＞") {
            guard let lower = numbers.first else { return nil }
            return v < lower ? .low : .normal
        }
        if numbers.count >= 2 {
            let lower = numbers[0]
            let upper = numbers[1]
            if v < lower { return .low }
            if v > upper { return .high }
            return .normal
        }
        return nil
    }

    private static func firstNumber(in text: String) -> Double? {
        numbers(in: text).first
    }

    private static func numbers(in text: String) -> [Double] {
        let pattern = #"-?\d+(?:\.\d+)?"#
        guard let regex = try? NSRegularExpression(pattern: pattern) else { return [] }
        let ns = text as NSString
        let range = NSRange(location: 0, length: ns.length)
        return regex.matches(in: text, range: range).compactMap {
            Double(ns.substring(with: $0.range))
        }
    }
}

// MARK: - Report ↔ CaptureService 桥接(MainActor 侧)
//
// CaptureService 是 actor,不能直接收 Report(@Model 非 Sendable)。
// C2「重新解读」UI 走这条路径:
// ```
// let assets = report.savedAssets
// let parsed = try await CaptureService.shared.reanalyze(assets: assets)
// report.applyReanalyzed(parsed, in: ctx)
// ```

extension Report {
    /// 关联 Asset 转 SavedAsset,直接喂 CaptureService.reanalyze。
    var savedAssets: [FileVault.SavedAsset] {
        assets.map { .init(relativePath: $0.relativePath, bytes: $0.bytes) }
    }

    /// 把 VL 重新识别结果写回 Report。
    /// - indicators:旧的全删,新的整批插入并维持关联(cascade delete 会清缓存)
    /// - summary / institution:非空才覆盖,避免空摘要把好结果清掉
    /// 必须在 MainActor / SwiftData 主上下文里调用。
    @MainActor
    func applyReanalyzed(_ parsed: ParsedReport, in ctx: ModelContext) {
        if !parsed.summary.isEmpty {
            self.summary = parsed.summary
        }
        if !parsed.institution.isEmpty {
            self.institution = parsed.institution
        }
        // 旧 indicators 全删。各自挂的 Asset(若有局部快拍图)关系是 nullify 不 cascade,
        // 必须手动 unlink Vault 文件 + 删 Asset 记录,否则留下孤儿图片(违反 §6 隐私承诺)。
        // 对照正确写法见 TimelineEntryDetailView.deleteIndicator。
        for old in indicators {
            if let asset = old.asset {
                try? FileVault.shared.remove(relativePath: asset.relativePath)
                ctx.delete(asset)
            }
            ctx.delete(old)
        }
        indicators.removeAll()
        // 新 indicators 重新插入
        for p in parsed.indicators {
            let i = Indicator(
                name: p.name,
                value: p.value,
                unit: p.unit,
                range: p.range,
                status: p.status,
                capturedAt: reportDate,
                report: self,
                source: .report,
                sourcePageIndex: p.sourcePageIndex,
                sourceBoxX: p.sourceBoxX,
                sourceBoxY: p.sourceBoxY,
                sourceBoxWidth: p.sourceBoxWidth,
                sourceBoxHeight: p.sourceBoxHeight
            )
            ctx.insert(i)
        }
        try? ctx.save()
    }
}