import SwiftUI
import SwiftData
import UIKit

/// 「拍药盒入档」流程:拍药盒/说明书 → Vision OCR → LLM 结构化 → 核对 → 落库。
/// 入口:「+ 新建 · 健康日记 · 拍药盒」与「我的 · 个人资料 · 当前用药」。
/// 两个入口确认后都走 `MedicationArchiver`:记一条「用药」日记(进记录时间线)+ 同步当前用药。
/// 只识别入档,不做用药提醒/剂量建议(§1)。
///
/// 状态机(与 QuickRegionCaptureFlow 同构):
/// ```
/// idle(相机/相册) → recognizing(OCR + LLM) → confirm(核对可编辑) → onSave → 关闭
///                          │ 失败/没读出 ──────► confirm(空行 + 警示文案,手动补)
/// ```
struct MedicationScanFlow: View {
    /// 用户确认后回传条目文本(非空,如 "缬沙坦胶囊 80mg · 一日一次")。落库由调用方做。
    let onSave: ([String]) -> Void
    let onClose: () -> Void

    @State private var phase: Phase = .idle
    /// 识别任务句柄:识别中点「取消」要能立刻中断,不留后台推理。
    @State private var recognitionTask: Task<Void, Never>?

    enum Phase {
        case idle
        case recognizing(image: UIImage)
        case confirm(items: [EditableMedication], warning: String?)
    }

    struct EditableMedication: Identifiable {
        let id = UUID()
        var name: String
        var strength: String
        var usage: String
        var include: Bool = true
    }

    var body: some View {
        content
            .background(Tj.Palette.sand.ignoresSafeArea())
    }

    @ViewBuilder
    private var content: some View {
        switch phase {
        case .idle:
            // 不整体 ignoresSafeArea:相机内部已全屏黑底,忽略安全区会让「取消」顶进灵动岛。
            captureEntry

        case .recognizing(let image):
            recognizingView(image: image)

        case .confirm(let items, let warning):
            NavigationStack {
                MedicationConfirmView(
                    items: items,
                    warning: warning,
                    onSave: { saveItems($0) },
                    onRetake: { phase = .idle }
                )
                .navigationTitle("核对药品")
                .navigationBarTitleDisplayMode(.inline)
                .toolbar {
                    ToolbarItem(placement: .topBarLeading) {
                        Button("取消") { onClose() }
                            .foregroundStyle(Tj.Palette.text)
                    }
                }
            }
        }
    }

    // MARK: - 入口:拍照(真机)/ 相册(模拟器)

    @ViewBuilder
    private var captureEntry: some View {
        #if targetEnvironment(simulator)
        PhotoPickerSheet(
            onFinish: { images in
                if let first = images.first { startRecognition(first) } else { onClose() }
            },
            onCancel: onClose
        )
        #else
        SingleShotCameraView(
            onCapture: { startRecognition($0) },
            onCancel: onClose
        )
        #endif
    }

    private func recognizingView(image: UIImage) -> some View {
        VStack(spacing: 18) {
            Image(uiImage: image)
                .resizable()
                .scaledToFit()
                .frame(maxHeight: 320)
                .clipShape(RoundedRectangle(cornerRadius: Tj.Radius.md, style: .continuous))
                .padding(.horizontal, 24)
            ProgressView().tint(Tj.Palette.ink)
            Text("正在本地识别药品…")
                .font(.tjScaled(14))
                .foregroundStyle(Tj.Palette.text2)
            Text("照片与文字均不离开设备")
                .font(.tjScaled(12))
                .foregroundStyle(Tj.Palette.text3)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        // 识别中也要能退出,不能让用户干等(§3.2 不卡死)
        .overlay(alignment: .topLeading) {
            Button {
                recognitionTask?.cancel()
                onClose()
            } label: {
                Text("取消")
                    .font(.tjScaled( 16, weight: .medium))
                    .foregroundStyle(Tj.Palette.text)
                    .padding(.horizontal, 18)
                    .frame(minHeight: 44)
                    .background(Capsule().fill(Tj.Palette.paper))
                    .overlay(Capsule().strokeBorder(Tj.Palette.line, lineWidth: 1))
                    .contentShape(Capsule())
            }
            .buttonStyle(.plain)
            .padding(.leading, 16)
            .padding(.top, 8)
        }
    }

    // MARK: - 识别(整图 OCR → LLM 结构化)

    private func startRecognition(_ image: UIImage) {
        phase = .recognizing(image: image)
        recognitionTask = Task {
            let (items, warning) = await recognize(image)
            guard !Task.isCancelled else { return }   // 识别中点了取消:不再回写 phase
            await MainActor.run {
                // 全失败也不卡死:给一条空行让用户手填(§3.2 失败回退红线)。
                if items.isEmpty {
                    phase = .confirm(items: [EditableMedication(name: "", strength: "", usage: "")],
                                     warning: warning ?? String(appLoc: "没读出药品,可以手动填写"))
                } else {
                    phase = .confirm(items: items, warning: warning)
                }
            }
        }
    }

    private func recognize(_ image: UIImage) async -> (items: [EditableMedication], warning: String?) {
        do {
            let text = try await OCRService.recognizeText(in: image)
            let trimmed = text.trimmingCharacters(in: .whitespacesAndNewlines)
            if trimmed.isEmpty {
                return ([], String(appLoc: "没识别到文字,拍清楚一点再试"))
            }
            let parsed = try await MedicationScanService.shared.recognizeMedications(fromOCRText: trimmed)
            let items = parsed.map {
                EditableMedication(name: $0.name, strength: $0.strength, usage: $0.usage)
            }
            return (items, items.isEmpty ? String(appLoc: "没读出药品,可以手动填写") : nil)
        } catch CaptureError.modelNotReady {
            return ([], String(appLoc: "AI 模型未就绪,可以手动填写"))
        } catch let CaptureError.parseFailed(msg) {
            return ([], String(appLoc: "解析失败:\(msg)"))
        } catch let CaptureError.inferenceFailed(msg) {
            return ([], String(appLoc: "识别失败:\(msg)"))
        } catch {
            return ([], String(appLoc: "未知错误:\(error.localizedDescription)"))
        }
    }

    // MARK: - 保存

    private func saveItems(_ items: [EditableMedication]) {
        let entries = items
            .filter { $0.include && !$0.name.trimmingCharacters(in: .whitespaces).isEmpty }
            .map {
                ParsedMedication(name: $0.name, strength: $0.strength, usage: $0.usage).entryText
            }
        onSave(entries)
        onClose()
    }
}

// MARK: - 统一落库(MainActor,SwiftData 写主上下文必须由 View 侧持有的 ctx 来做,§3.1)

/// 拍药盒确认后的统一落库,两个入口共用:
/// 1. 记一条带「用药」tag 的 DiaryEntry → 出现在「记录」时间线的「用药」分类
/// 2. 同步到 UserProfile.currentMedications(去重)→ AI 解读 / 身体档案 prompt 背景
@MainActor
enum MedicationArchiver {
    static func archive(entries: [String], in ctx: ModelContext) {
        guard !entries.isEmpty else { return }
        let diary = DiaryEntry(content: entries.joined(separator: "\n"),
                               tags: [DiaryEntry.medicationTag])
        ctx.insert(diary)

        let profile = UserProfileStore.loadOrCreate(in: ctx)
        for entry in entries where !profile.currentMedications.contains(entry) {
            profile.currentMedications.append(entry)
        }
        profile.updatedAt = .now
        try? ctx.save()
    }
}

// MARK: - 核对页

private struct MedicationConfirmView: View {
    @State var items: [MedicationScanFlow.EditableMedication]
    let warning: String?
    let onSave: ([MedicationScanFlow.EditableMedication]) -> Void
    let onRetake: () -> Void

    private var canSave: Bool {
        items.contains {
            $0.include && !$0.name.trimmingCharacters(in: .whitespaces).isEmpty
        }
    }

    var body: some View {
        VStack(spacing: 0) {
            Form {
                if let warning {
                    Section {
                        Label(warning, systemImage: "exclamationmark.triangle")
                            .font(.tjScaled(13))
                            .foregroundStyle(Tj.Palette.amber)
                    }
                }

                ForEach($items) { $item in
                    Section {
                        HStack {
                            TextField(String(appLoc: "药品名,如:缬沙坦胶囊"), text: $item.name)
                                .foregroundStyle(Tj.Palette.text)
                            Toggle("", isOn: $item.include)
                                .labelsHidden()
                                .tint(Tj.Palette.ink)
                        }
                        TextField(String(appLoc: "规格,如:80mg×7粒"), text: $item.strength)
                            .foregroundStyle(Tj.Palette.text2)
                        TextField(String(appLoc: "用法,如:一日一次,一次一粒"), text: $item.usage)
                            .foregroundStyle(Tj.Palette.text2)
                    }
                }

                Section {
                    Button {
                        items.append(.init(name: "", strength: "", usage: ""))
                    } label: {
                        Label("再加一种", systemImage: "plus.circle")
                            .foregroundStyle(Tj.Palette.ink)
                    }
                    Button {
                        onRetake()
                    } label: {
                        Label("重拍", systemImage: "camera")
                            .foregroundStyle(Tj.Palette.ink)
                    }
                } footer: {
                    Text("将记入健康日记(记录页可查),并同步到「当前用药」供 AI 解读参考。不提供任何用药建议。")
                }
            }
            .scrollContentBackground(.hidden)

            Button {
                onSave(items)
            } label: {
                Text("保存用药记录")
                    .frame(maxWidth: .infinity)
            }
            .buttonStyle(TjPrimaryButton())
            .disabled(!canSave)
            .opacity(canSave ? 1 : 0.4)
            .padding(.horizontal, 18)
            .padding(.bottom, 12)
        }
        .background(Tj.Palette.sand.ignoresSafeArea())
    }
}

#Preview {
    MedicationScanFlow(onSave: { print($0) }, onClose: {})
}