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

import SwiftUI

/// The chat detail column: 52 pt header, centered transcript, floating input.
struct ChatView: View {
    @Environment(AppModel.self) private var app

    var body: some View {
        Group {
            if app.store.models.isEmpty && app.downloads.tasks.isEmpty {
                OnboardingHeroView()
            } else if let conversation = app.selectedConversation {
                chatBody(conversation)
            } else {
                emptySelection
            }
        }
        .background(ZyquoTheme.background)
    }

    @ViewBuilder
    private func chatBody(_ conversation: Conversation) -> some View {
        VStack(spacing: 0) {
            ChatHeaderView(conversation: conversation)
            Rectangle().fill(ZyquoTheme.border).frame(height: ZyquoTheme.hairline)

            ZStack {
                TranscriptView(conversation: conversation)
                if case .loading(let repoID) = app.engineState {
                    ModelLoadingCard(repoID: repoID)
                }
            }

            InputBar(conversation: conversation)
        }
    }

    private var emptySelection: some View {
        VStack(spacing: ZyquoTheme.Spacing.s) {
            ZyquoGlyph(size: 40, color: ZyquoTheme.textTertiary)
            Text("Select a chat or press ⌘N")
                .font(ZyquoTheme.body)
                .foregroundStyle(ZyquoTheme.textSecondary)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
    }
}

/// Elegant centered card while a model loads; input is disabled meanwhile.
struct ModelLoadingCard: View {
    let repoID: String
    @State private var appeared = false

    var body: some View {
        VStack(spacing: ZyquoTheme.Spacing.m) {
            ProgressView()
                .controlSize(.large)
                .tint(ZyquoTheme.accent)
            Text("Loading \(shortModelName(repoID))")
                .font(ZyquoTheme.bodyEmphasis)
                .foregroundStyle(ZyquoTheme.textPrimary)
            Text("Allocating unified memory for the model weights…")
                .font(ZyquoTheme.caption)
                .foregroundStyle(ZyquoTheme.textSecondary)
        }
        .padding(ZyquoTheme.Spacing.xxl)
        .background(ZyquoTheme.surface, in: RoundedRectangle(cornerRadius: ZyquoTheme.Radius.l))
        .overlay(
            RoundedRectangle(cornerRadius: ZyquoTheme.Radius.l)
                .stroke(ZyquoTheme.border, lineWidth: ZyquoTheme.hairline)
        )
        .floatingShadow()
        .opacity(appeared ? 1 : 0)
        .offset(y: appeared ? 0 : 6)
        .onAppear {
            withAnimation(.easeOut(duration: 0.15)) { appeared = true }
        }
    }
}