//
//  SidebarView.swift
//  Zyquo Cloud
//
//  Author: Simon-Pierre Boucher
//  Mail: contact@spboucher.ai
//
//  Sidebar per the Phase 4 spec: wordmark, search field, prominent New Chat,
//  conversation list grouped Pinned/Today/Yesterday/Previous 7 Days/Older,
//  hover-revealed pin/delete, footer with settings + usage summary.
//

import SwiftUI

struct SidebarView: View {
    @EnvironmentObject private var store: ConversationStore
    @EnvironmentObject private var catalog: ModelCatalog
    @FocusState private var searchFocused: Bool
    @State private var activeTag: String?

    var body: some View {
        VStack(spacing: 0) {
            wordmark
            searchField
            newChatButton
            conversationList
            if !allTags.isEmpty {
                ZyquoHairline()
                tagsSection
            }
            ZyquoHairline()
            footer
        }
        .frame(minWidth: ZyquoMetrics.sidebarWidth)
        .background(
            // ⌘F focuses conversation search.
            Button("") { searchFocused = true }
                .keyboardShortcut("f", modifiers: .command)
                .hidden()
        )
    }

    // MARK: - Tags

    private var allTags: [String] {
        Array(Set(store.conversations.flatMap(\.tags))).sorted()
    }

    private var tagsSection: some View {
        ScrollView(.horizontal, showsIndicators: false) {
            HStack(spacing: ZyquoSpacing.xxs) {
                Image(systemName: "tag")
                    .font(.system(size: 9))
                    .foregroundStyle(ZyquoColor.textTertiary)
                ForEach(allTags, id: \.self) { tag in
                    Button {
                        activeTag = activeTag == tag ? nil : tag
                    } label: {
                        Text(tag)
                            .font(ZyquoFont.caption)
                            .foregroundStyle(activeTag == tag ? .white : ZyquoColor.textSecondary)
                            .padding(.horizontal, ZyquoSpacing.xs)
                            .padding(.vertical, 2)
                            .background(
                                Capsule().fill(activeTag == tag ? ZyquoColor.accent : ZyquoColor.surfaceSecondary)
                            )
                    }
                    .buttonStyle(.plain)
                }
            }
            .padding(.horizontal, ZyquoSpacing.sm)
            .padding(.vertical, ZyquoSpacing.xxs)
        }
    }

    // MARK: - Sections

    private var wordmark: some View {
        HStack(spacing: ZyquoSpacing.xs) {
            CloudZGlyph(size: 22)
            Text("Zyquo Cloud")
                .font(ZyquoFont.bodyEmphasis(size: 14))
                .foregroundStyle(ZyquoColor.textPrimary)
            Spacer()
        }
        .padding(.horizontal, ZyquoMetrics.contentInset)
        .padding(.top, ZyquoSpacing.sm)
        .padding(.bottom, ZyquoSpacing.xs)
    }

    private var searchField: some View {
        HStack(spacing: ZyquoSpacing.xxs) {
            Image(systemName: "magnifyingglass")
                .font(.system(size: 11))
                .foregroundStyle(ZyquoColor.textTertiary)
            TextField("Search", text: $store.searchText)
                .textFieldStyle(.plain)
                .font(ZyquoFont.body(size: 12.5))
                .focused($searchFocused)
        }
        .padding(.horizontal, ZyquoSpacing.xs)
        .padding(.vertical, 5)
        .background(
            RoundedRectangle(cornerRadius: ZyquoRadius.small, style: .continuous)
                .fill(ZyquoColor.surfaceSecondary.opacity(0.7))
        )
        .padding(.horizontal, ZyquoSpacing.sm)
        .padding(.bottom, ZyquoSpacing.xs)
    }

    private var newChatButton: some View {
        Button {
            store.newConversation()
        } label: {
            HStack(spacing: ZyquoSpacing.xxs) {
                Image(systemName: "plus.bubble.fill")
                    .font(.system(size: 12, weight: .semibold))
                Text("New Chat")
                    .font(ZyquoFont.bodyEmphasis(size: 13))
            }
            .foregroundStyle(.white)
            .frame(maxWidth: .infinity)
            .padding(.vertical, 7)
            .background(
                RoundedRectangle(cornerRadius: ZyquoRadius.small, style: .continuous)
                    .fill(ZyquoColor.accent)
            )
        }
        .buttonStyle(PressableButtonStyle())
        .keyboardShortcut("n", modifiers: .command)
        .padding(.horizontal, ZyquoSpacing.sm)
        .padding(.bottom, ZyquoSpacing.xs)
    }

    /// Sidebar groups, additionally narrowed by the active tag chip.
    private var filteredGroups: [ConversationStore.SidebarGroup] {
        guard let tag = activeTag else { return store.sidebarGroups }
        return store.sidebarGroups.compactMap { group in
            let matching = group.conversations.filter { $0.tags.contains(tag) }
            return matching.isEmpty
                ? nil
                : ConversationStore.SidebarGroup(id: group.id, title: group.title, conversations: matching)
        }
    }

    private var conversationList: some View {
        ScrollView {
            LazyVStack(alignment: .leading, spacing: 2, pinnedViews: []) {
                ForEach(filteredGroups) { group in
                    Text(group.title)
                        .font(ZyquoFont.caption)
                        .foregroundStyle(ZyquoColor.textTertiary)
                        .padding(.horizontal, ZyquoSpacing.md)
                        .padding(.top, ZyquoSpacing.sm)
                        .padding(.bottom, 2)
                    ForEach(group.conversations) { conversation in
                        ConversationRow(conversation: conversation)
                    }
                }
            }
            .padding(.horizontal, ZyquoSpacing.xs)
            .padding(.bottom, ZyquoSpacing.sm)
        }
    }

    private var footer: some View {
        HStack {
            Button {
                SettingsOpener.open()
            } label: {
                Image(systemName: "gearshape")
                    .font(.system(size: 13))
                    .foregroundStyle(ZyquoColor.textSecondary)
            }
            .buttonStyle(.plain)
            .help("Settings")
            Spacer()
            Text(usageSummary)
                .font(ZyquoFont.caption)
                .foregroundStyle(ZyquoColor.textTertiary)
        }
        .padding(.horizontal, ZyquoMetrics.contentInset)
        .padding(.vertical, ZyquoSpacing.xs)
    }

    private var usageSummary: String {
        let tokens = store.conversations.map { $0.totalUsage.totalTokens }.reduce(0, +)
        let cost = store.conversations.map(\.totalCost).reduce(0, +)
        guard tokens > 0 else { return "" }
        let tokenText = tokens >= 1_000_000
            ? String(format: "%.1fM tok", Double(tokens) / 1_000_000)
            : String(format: "%.1fK tok", Double(tokens) / 1_000)
        return cost > 0 ? String(format: "%@ · ~$%.2f", tokenText, cost) : tokenText
    }
}

// MARK: - Row

private struct ConversationRow: View {
    let conversation: Conversation
    @EnvironmentObject private var store: ConversationStore
    @State private var hovering = false

    private var isSelected: Bool { store.selectedID == conversation.id }

    var body: some View {
        Button {
            store.selectedID = conversation.id
        } label: {
            HStack(spacing: ZyquoSpacing.xs) {
                VStack(alignment: .leading, spacing: 1) {
                    Text(conversation.title)
                        .font(ZyquoFont.body(size: 13))
                        .foregroundStyle(ZyquoColor.textPrimary)
                        .lineLimit(1)
                    HStack(spacing: ZyquoSpacing.xxs) {
                        Text(conversation.modelID)
                            .font(ZyquoFont.caption)
                            .foregroundStyle(ZyquoColor.textTertiary)
                            .lineLimit(1)
                        Text(conversation.updatedAt, format: .relative(presentation: .named))
                            .font(ZyquoFont.caption)
                            .foregroundStyle(ZyquoColor.textTertiary)
                    }
                }
                Spacer(minLength: 0)
                if hovering {
                    rowActions
                } else if conversation.isPinned {
                    Image(systemName: "pin.fill")
                        .font(.system(size: 9))
                        .foregroundStyle(ZyquoColor.textTertiary)
                }
            }
            .padding(.horizontal, ZyquoSpacing.xs)
            .padding(.vertical, 5)
            .background(
                RoundedRectangle(cornerRadius: ZyquoRadius.small, style: .continuous)
                    .fill(isSelected ? ZyquoColor.accentSubtle : (hovering ? ZyquoColor.surfaceSecondary.opacity(0.6) : .clear))
            )
            .contentShape(Rectangle())
        }
        .buttonStyle(.plain)
        .onHover { inside in
            withAnimation(ZyquoMotion.hover) { hovering = inside }
        }
        .contextMenu {
            Button(conversation.isPinned ? "Unpin" : "Pin") { store.togglePin(conversation.id) }
            Button("Add Tag…") { promptForTag() }
            if !conversation.tags.isEmpty {
                Menu("Remove Tag") {
                    ForEach(conversation.tags, id: \.self) { tag in
                        Button(tag) {
                            guard var updated = store.conversations.first(where: { $0.id == conversation.id }) else { return }
                            updated.tags.removeAll { $0 == tag }
                            store.update(updated)
                        }
                    }
                }
            }
            Button("Delete", role: .destructive) { store.delete(conversation.id) }
        }
    }

    private func promptForTag() {
        let alert = NSAlert()
        alert.messageText = "Add Tag"
        alert.informativeText = "Tags group conversations in the sidebar."
        let field = NSTextField(frame: NSRect(x: 0, y: 0, width: 220, height: 22))
        field.placeholderString = "Tag name"
        alert.accessoryView = field
        alert.addButton(withTitle: "Add")
        alert.addButton(withTitle: "Cancel")
        guard alert.runModal() == .alertFirstButtonReturn else { return }
        let tag = field.stringValue.trimmingCharacters(in: .whitespaces)
        guard !tag.isEmpty,
              var updated = store.conversations.first(where: { $0.id == conversation.id }),
              !updated.tags.contains(tag)
        else { return }
        updated.tags.append(tag)
        store.update(updated)
    }

    private var rowActions: some View {
        HStack(spacing: ZyquoSpacing.xxs) {
            Button {
                store.togglePin(conversation.id)
            } label: {
                Image(systemName: conversation.isPinned ? "pin.slash" : "pin")
                    .font(.system(size: 10))
                    .foregroundStyle(ZyquoColor.textSecondary)
            }
            .buttonStyle(.plain)
            .help(conversation.isPinned ? "Unpin" : "Pin")
            Button {
                store.delete(conversation.id)
            } label: {
                Image(systemName: "trash")
                    .font(.system(size: 10))
                    .foregroundStyle(ZyquoColor.textSecondary)
            }
            .buttonStyle(.plain)
            .help("Delete")
        }
    }
}