import SwiftUI
import SwiftData

/// 计算属性形式:每次取值按当前语言解析,语言切换后即时更新(不可用 static/let 缓存)。
private func symptomPresets() -> [String] {
    [String(appLoc: "头痛"), String(appLoc: "咳嗽"), String(appLoc: "腹痛"), String(appLoc: "发烧"),
     String(appLoc: "恶心"), String(appLoc: "失眠"), String(appLoc: "疲劳"), String(appLoc: "关节痛")]
}

struct SymptomStartSheet: View {
    @Environment(\.modelContext) private var ctx
    @Environment(\.dismiss) private var dismiss

    @State private var name: String = ""
    @State private var customName: String = ""
    @State private var startedAt: Date = .now
    @State private var severity: Double = 3
    @State private var note: String = ""

    private var resolvedName: String {
        let trimmed = customName.trimmingCharacters(in: .whitespaces)
        return trimmed.isEmpty ? name : trimmed
    }

    private var canSubmit: Bool { !resolvedName.isEmpty }

    var body: some View {
        VStack(spacing: 0) {
            handle
            header

            ScrollView(showsIndicators: false) {
                VStack(alignment: .leading, spacing: 18) {
                    presetSection
                    customSection
                    timeSection
                    severitySection
                    noteSection
                }
                .padding(.horizontal, 20)
                .padding(.bottom, 20)
            }

            footer
        }
        .background(
            Tj.Palette.sand
                .clipShape(RoundedRectangle(cornerRadius: Tj.Radius.xl, style: .continuous))
                .ignoresSafeArea(edges: .bottom)
        )
        .presentationDetents([.large])
        .presentationDragIndicator(.hidden)
        .presentationBackground(Tj.Palette.sand)
        .presentationCornerRadius(Tj.Radius.xl)
    }

    private var handle: some View {
        Capsule()
            .fill(Tj.Palette.line)
            .frame(width: 40, height: 4)
            .padding(.top, 10)
            .padding(.bottom, 14)
    }

    private var header: some View {
        HStack {
            Text("症状开始")
                .font(.tjH2())
                .foregroundStyle(Tj.Palette.text)
            Spacer()
            Text("结束时再来点结束")
                .font(.system(size: 12))
                .foregroundStyle(Tj.Palette.text3)
        }
        .padding(.horizontal, 20)
        .padding(.bottom, 16)
    }

    private var presetSection: some View {
        VStack(alignment: .leading, spacing: 8) {
            sectionLabel(String(appLoc: "常见症状"))
            ScrollView(.horizontal, showsIndicators: false) {
                HStack(spacing: 8) {
                    ForEach(symptomPresets(), id: \.self) { item in
                        chip(item, selected: name == item) {
                            name = item
                            customName = ""
                        }
                    }
                }
            }
        }
    }

    private var customSection: some View {
        VStack(alignment: .leading, spacing: 8) {
            sectionLabel(String(appLoc: "或者自己写"))
            TextField("例如：眼皮跳", text: $customName)
                .textInputAutocapitalization(.never)
                .padding(.horizontal, 14)
                .padding(.vertical, 12)
                .background(
                    RoundedRectangle(cornerRadius: Tj.Radius.sm, style: .continuous)
                        .fill(Tj.Palette.paper)
                )
                .overlay(
                    RoundedRectangle(cornerRadius: Tj.Radius.sm, style: .continuous)
                        .strokeBorder(Tj.Palette.line, lineWidth: 1)
                )
                .onChange(of: customName) { _, newValue in
                    if !newValue.trimmingCharacters(in: .whitespaces).isEmpty {
                        name = ""
                    }
                }
        }
    }

    private var timeSection: some View {
        VStack(alignment: .leading, spacing: 8) {
            sectionLabel(String(appLoc: "开始时间"))
            DatePicker("", selection: $startedAt, in: ...Date.now)
                .datePickerStyle(.compact)
                .labelsHidden()
        }
    }

    private var severitySection: some View {
        VStack(alignment: .leading, spacing: 8) {
            HStack {
                sectionLabel(String(appLoc: "强度"))
                Spacer()
                Text("\(Int(severity)) / 5")
                    .font(.system(size: 13, weight: .semibold, design: .monospaced))
                    .foregroundStyle(severityColor)
            }
            Slider(value: $severity, in: 1...5, step: 1)
                .tint(severityColor)
            HStack {
                Text("轻微").font(.system(size: 11)).foregroundStyle(Tj.Palette.text3)
                Spacer()
                Text("剧烈").font(.system(size: 11)).foregroundStyle(Tj.Palette.text3)
            }
        }
    }

    private var noteSection: some View {
        VStack(alignment: .leading, spacing: 8) {
            sectionLabel(String(appLoc: "备注（可选）"))
            TextField("位置、可能诱因…", text: $note, axis: .vertical)
                .lineLimit(2...4)
                .padding(.horizontal, 14)
                .padding(.vertical, 12)
                .background(
                    RoundedRectangle(cornerRadius: Tj.Radius.sm, style: .continuous)
                        .fill(Tj.Palette.paper)
                )
                .overlay(
                    RoundedRectangle(cornerRadius: Tj.Radius.sm, style: .continuous)
                        .strokeBorder(Tj.Palette.line, lineWidth: 1)
                )
        }
    }

    private var footer: some View {
        HStack(spacing: 12) {
            Button("取消") { dismiss() }
                .buttonStyle(TjGhostButton(height: 44, fontSize: 15, horizontalPadding: 18))
            Button("开始记录") { submit() }
                .buttonStyle(TjPrimaryButton(height: 44, fontSize: 15, horizontalPadding: 18))
                .disabled(!canSubmit)
                .opacity(canSubmit ? 1 : 0.4)
        }
        .padding(.horizontal, 20)
        .padding(.vertical, 14)
        .background(
            Tj.Palette.sand
                .overlay(alignment: .top) {
                    Rectangle().fill(Tj.Palette.lineSoft).frame(height: 1)
                }
        )
    }

    private var severityColor: Color {
        switch Int(severity) {
        case 1, 2: return Tj.Palette.leaf
        case 3:    return Tj.Palette.amber
        default:   return Tj.Palette.brick
        }
    }

    private func sectionLabel(_ text: String) -> some View {
        Text(text)
            .font(.system(size: 12, weight: .semibold))
            .tracking(0.3)
            .foregroundStyle(Tj.Palette.text2)
    }

    private func chip(_ label: String, selected: Bool, action: @escaping () -> Void) -> some View {
        Button(action: action) {
            Text(label)
                .font(.system(size: 13, weight: selected ? .semibold : .regular))
                .foregroundStyle(selected ? Tj.Palette.paper : Tj.Palette.text)
                .padding(.horizontal, 14)
                .padding(.vertical, 8)
                .background(
                    Capsule().fill(selected ? Tj.Palette.ink : Tj.Palette.paper)
                )
                .overlay(
                    Capsule().strokeBorder(Tj.Palette.line, lineWidth: selected ? 0 : 1)
                )
        }
        .buttonStyle(.plain)
    }

    private func submit() {
        guard canSubmit else { return }
        let symptom = Symptom(
            name: resolvedName,
            startedAt: startedAt,
            note: note.trimmingCharacters(in: .whitespaces).isEmpty ? nil : note,
            severity: Int(severity)
        )
        ctx.insert(symptom)
        try? ctx.save()
        dismiss()
    }
}

#Preview {
    SymptomStartSheet()
        .modelContainer(for: Symptom.self, inMemory: true)
}