//
//  ChatHeaderView.swift
//  Zyquo Local
//
//  Author: Simon-Pierre Boucher
//  Mail: contact@spboucher.ai
//

import SwiftUI

/// 52 pt header: editable title · centered model chip · perf toggle, export,
/// info popover (system prompt, params, context usage bar).
struct ChatHeaderView: View {
    let conversation: Conversation
    @Environment(AppModel.self) private var app
    @State private var title = ""
    @State private var showInfo = false
    @State private var showPerf = true
    @State private var contextUsage: (used: Int, window: Int)?

    var body: some View {
        HStack(spacing: ZyquoTheme.Spacing.s) {
            // Editable title (left)
            TextField(
                "Title", text: $title,
                onCommit: {
                    var c = conversation
                    c.title = title.isEmpty ? conversation.title : title
                    app.update(c, touch: false)
                }
            )
            .textFieldStyle(.plain)
            .font(ZyquoTheme.bodyEmphasis)
            .foregroundStyle(ZyquoTheme.textPrimary)
            .frame(maxWidth: 220, alignment: .leading)
            .onAppear { title = conversation.title }
            .onChange(of: conversation.id) { title = conversation.title }
            .onChange(of: conversation.title) { title = conversation.title }

            Spacer()

            ModelChipView(conversation: conversation)

            Spacer()

            // Live perf while generating
            if showPerf, app.chat.isGenerating, app.chat.liveTokensPerSecond > 0 {
                Text(String(format: "%.1f tok/s", app.chat.liveTokensPerSecond))
                    .font(ZyquoTheme.caption.monospacedDigit())
                    .foregroundStyle(ZyquoTheme.accent)
                    .transition(.opacity)
            }

            Button {
                showPerf.toggle()
            } label: {
                Image(systemName: "gauge.with.dots.needle.67percent")
                    .foregroundStyle(showPerf ? ZyquoTheme.accent : ZyquoTheme.textSecondary)
            }
            .buttonStyle(.plain)
            .help("Show live tokens/sec while generating")

            Menu {
                Button("Export as Markdown…") { ExportService.exportMarkdown(conversation) }
                Button("Export as PDF…") { ExportService.exportPDF(conversation) }
            } label: {
                Image(systemName: "square.and.arrow.up")
                    .foregroundStyle(ZyquoTheme.textSecondary)
            }
            .menuStyle(.borderlessButton)
            .menuIndicator(.hidden)
            .frame(width: 24)
            .help("Export conversation (⇧⌘E)")

            Button {
                Task { contextUsage = await app.engine.contextUsage }
                showInfo.toggle()
            } label: {
                Image(systemName: "info.circle")
                    .foregroundStyle(ZyquoTheme.textSecondary)
            }
            .buttonStyle(.plain)
            .popover(isPresented: $showInfo, arrowEdge: .bottom) {
                ConversationInfoPopover(conversation: conversation, contextUsage: contextUsage)
            }
            .help("Conversation settings")
        }
        .padding(.horizontal, ZyquoTheme.Spacing.m)
        .frame(height: ZyquoTheme.chatHeaderHeight)
        .background(ZyquoTheme.background)
        .onReceive(NotificationCenter.default.publisher(for: .zyquoExportConversation)) { _ in
            ExportService.exportMarkdown(conversation)
        }
    }
}

/// Info popover: system prompt, per-conversation params, context usage bar.
struct ConversationInfoPopover: View {
    let conversation: Conversation
    let contextUsage: (used: Int, window: Int)?
    @Environment(AppModel.self) private var app
    @State private var systemPrompt = ""

    var body: some View {
        VStack(alignment: .leading, spacing: ZyquoTheme.Spacing.m) {
            Text("Conversation")
                .font(ZyquoTheme.bodyEmphasis)

            VStack(alignment: .leading, spacing: ZyquoTheme.Spacing.xxs) {
                Text("System prompt")
                    .font(ZyquoTheme.caption)
                    .foregroundStyle(ZyquoTheme.textSecondary)
                TextEditor(text: $systemPrompt)
                    .font(ZyquoTheme.body)
                    .frame(height: 72)
                    .scrollContentBackground(.hidden)
                    .padding(ZyquoTheme.Spacing.xxs)
                    .background(ZyquoTheme.surfaceSecondary, in: RoundedRectangle(cornerRadius: ZyquoTheme.Radius.s))
                    .onChange(of: systemPrompt) {
                        var c = conversation
                        c.systemPrompt = systemPrompt.isEmpty ? nil : systemPrompt
                        app.update(c, touch: false)
                    }
            }

            ParamsEditor(
                params: Binding(
                    get: { app.selectedConversation?.params ?? conversation.params },
                    set: { newParams in
                        var c = app.selectedConversation ?? conversation
                        c.params = newParams
                        app.update(c, touch: false)
                    }
                )
            )

            if let usage = contextUsage, usage.window > 0 {
                VStack(alignment: .leading, spacing: ZyquoTheme.Spacing.xxs) {
                    HStack {
                        Text("Context")
                            .font(ZyquoTheme.caption)
                            .foregroundStyle(ZyquoTheme.textSecondary)
                        Spacer()
                        Text("≈\(usage.used) / \(usage.window) tokens")
                            .font(ZyquoTheme.caption.monospacedDigit())
                            .foregroundStyle(ZyquoTheme.textSecondary)
                    }
                    ProgressView(value: min(1, Double(usage.used) / Double(usage.window)))
                        .tint(usage.used > usage.window * 3 / 4 ? ZyquoTheme.warning : ZyquoTheme.accent)
                }
            }
        }
        .padding(ZyquoTheme.Spacing.m)
        .frame(width: 340)
        .onAppear { systemPrompt = conversation.systemPrompt ?? "" }
    }
}

/// Inline editors for the generation parameters, with plain-language help.
struct ParamsEditor: View {
    @Binding var params: GenerationParams

    var body: some View {
        VStack(alignment: .leading, spacing: ZyquoTheme.Spacing.xs) {
            slider(
                "Temperature", value: Binding(
                    get: { Double(params.temperature) },
                    set: { params.temperature = Float($0) }),
                range: 0...2, format: "%.2f",
                help: "Higher = more creative, lower = more focused")
            slider(
                "Top-p", value: Binding(
                    get: { Double(params.topP) },
                    set: { params.topP = Float($0) }),
                range: 0.05...1, format: "%.2f",
                help: "Nucleus sampling probability mass")
            slider(
                "Repetition penalty", value: Binding(
                    get: { Double(params.repetitionPenalty ?? 1.0) },
                    set: { params.repetitionPenalty = $0 <= 1.001 ? nil : Float($0) }),
                range: 1...1.5, format: "%.2f",
                help: "Discourages repeating recent tokens (1 = off)")
            HStack {
                Text("Max tokens")
                    .font(ZyquoTheme.caption)
                    .foregroundStyle(ZyquoTheme.textSecondary)
                Spacer()
                TextField(
                    "∞",
                    text: Binding(
                        get: { params.maxTokens.map(String.init) ?? "" },
                        set: { params.maxTokens = Int($0).flatMap { $0 > 0 ? $0 : nil } }
                    )
                )
                .textFieldStyle(.roundedBorder)
                .frame(width: 80)
                .multilineTextAlignment(.trailing)
                .font(ZyquoTheme.caption.monospacedDigit())
            }
            HStack {
                Text("Seed")
                    .font(ZyquoTheme.caption)
                    .foregroundStyle(ZyquoTheme.textSecondary)
                Spacer()
                TextField(
                    "random",
                    text: Binding(
                        get: { params.seed.map(String.init) ?? "" },
                        set: { params.seed = UInt64($0) }
                    )
                )
                .textFieldStyle(.roundedBorder)
                .frame(width: 110)
                .multilineTextAlignment(.trailing)
                .font(ZyquoTheme.caption.monospacedDigit())
            }
        }
    }

    @ViewBuilder
    private func slider(
        _ label: String, value: Binding<Double>, range: ClosedRange<Double>,
        format: String, help: String
    ) -> some View {
        VStack(alignment: .leading, spacing: 2) {
            HStack {
                Text(label)
                    .font(ZyquoTheme.caption)
                    .foregroundStyle(ZyquoTheme.textSecondary)
                Spacer()
                Text(String(format: format, value.wrappedValue))
                    .font(ZyquoTheme.caption.monospacedDigit())
                    .foregroundStyle(ZyquoTheme.textPrimary)
            }
            Slider(value: value, in: range)
                .controlSize(.mini)
                .tint(ZyquoTheme.accent)
        }
        .help(help)
    }
}