//
//  ConversationListView.swift
//  oAI
//
//  Saved conversations list
//

import os
import SwiftUI

struct ConversationListView: View {
    @Environment(\.dismiss) var dismiss
    @State private var searchText = ""
    @State private var conversations: [Conversation] = []
    @State private var selectedConversations: Set<UUID> = []
    @State private var isSelecting = false
    @State private var useSemanticSearch = false
    @State private var semanticResults: [Conversation] = []
    @State private var isSearching = false
    @State private var selectedIndex: Int = 0
    @FocusState private var searchFocused: Bool
    private let settings = SettingsService.shared
    var onLoad: ((Conversation) -> Void)?

    private var filteredConversations: [Conversation] {
        if searchText.isEmpty {
            return conversations
        }

        if useSemanticSearch && settings.embeddingsEnabled {
            return semanticResults
        } else {
            return conversations.filter {
                $0.name.lowercased().contains(searchText.lowercased())
            }
        }
    }

    var body: some View {
        VStack(spacing: 0) {
            // Header
            HStack {
                Text("Conversations")
                    .font(.system(size: 18, weight: .bold))
                Spacer()

                if isSelecting {
                    Button("Cancel") {
                        isSelecting = false
                        selectedConversations.removeAll()
                    }
                    .buttonStyle(.plain)

                    if !selectedConversations.isEmpty {
                        Button(role: .destructive) {
                            deleteSelected()
                        } label: {
                            HStack(spacing: 4) {
                                Image(systemName: "trash")
                                Text("Delete (\(selectedConversations.count))")
                            }
                        }
                        .buttonStyle(.plain)
                        .foregroundStyle(.red)
                    }
                } else {
                    if !conversations.isEmpty {
                        Button("Select") {
                            isSelecting = true
                        }
                        .buttonStyle(.plain)
                    }

                    Button { dismiss() } label: {
                        Image(systemName: "xmark.circle.fill")
                            .font(.title2)
                            .foregroundStyle(.secondary)
                    }
                    .buttonStyle(.plain)
                    .keyboardShortcut(.escape, modifiers: [])
                }
            }
            .padding(.horizontal, 24)
            .padding(.top, 20)
            .padding(.bottom, 12)

            // Search bar
            HStack(spacing: 8) {
                Image(systemName: "magnifyingglass")
                    .foregroundStyle(.secondary)
                TextField("Search conversations...", text: $searchText)
                    .textFieldStyle(.plain)
                    .focused($searchFocused)
                    .onChange(of: searchText) {
                        selectedIndex = 0
                        if useSemanticSearch && settings.embeddingsEnabled && !searchText.isEmpty {
                            performSemanticSearch()
                        }
                    }
                    #if os(macOS)
                    .onKeyPress(.upArrow) {
                        if selectedIndex > 0 {
                            selectedIndex -= 1
                        }
                        return .handled
                    }
                    .onKeyPress(.downArrow) {
                        if selectedIndex < filteredConversations.count - 1 {
                            selectedIndex += 1
                        }
                        return .handled
                    }
                    .onKeyPress(.return, phases: .down) { _ in
                        guard !isSelecting, !filteredConversations.isEmpty else { return .ignored }
                        let conv = filteredConversations[min(selectedIndex, filteredConversations.count - 1)]
                        onLoad?(conv)
                        dismiss()
                        return .handled
                    }
                    #endif
                if !searchText.isEmpty {
                    Button { searchText = "" } label: {
                        Image(systemName: "xmark.circle.fill")
                            .foregroundStyle(.tertiary)
                    }
                    .buttonStyle(.plain)
                }

                if settings.embeddingsEnabled {
                    Divider()
                        .frame(height: 16)
                    Toggle("Semantic", isOn: $useSemanticSearch)
                        .toggleStyle(.switch)
                        .controlSize(.small)
                        .onChange(of: useSemanticSearch) {
                            if useSemanticSearch && !searchText.isEmpty {
                                performSemanticSearch()
                            }
                        }
                        .help("Use AI-powered semantic search instead of keyword matching")
                }

                if isSearching {
                    ProgressView()
                        .controlSize(.small)
                }
            }
            .padding(10)
            .background(.quaternary.opacity(0.5), in: RoundedRectangle(cornerRadius: 8))
            .padding(.horizontal, 24)
            .padding(.bottom, 12)

            Divider()

            // Content
            if filteredConversations.isEmpty {
                Spacer()
                VStack(spacing: 8) {
                    Image(systemName: searchText.isEmpty ? "tray" : "magnifyingglass")
                        .font(.largeTitle)
                        .foregroundStyle(.tertiary)
                    Text(searchText.isEmpty ? "No Saved Conversations" : "No Matches")
                        .font(.headline)
                        .foregroundStyle(.secondary)
                    Text(searchText.isEmpty ? "Conversations you save will appear here" : "Try a different search term")
                        .font(.caption)
                        .foregroundStyle(.tertiary)
                }
                Spacer()
            } else {
                ScrollViewReader { proxy in
                    List {
                        ForEach(Array(filteredConversations.enumerated()), id: \.element.id) { index, conversation in
                            HStack(spacing: 12) {
                                if isSelecting {
                                    Button {
                                        toggleSelection(conversation.id)
                                    } label: {
                                        Image(systemName: selectedConversations.contains(conversation.id) ? "checkmark.circle.fill" : "circle")
                                            .foregroundStyle(selectedConversations.contains(conversation.id) ? .blue : .secondary)
                                            .font(.title2)
                                    }
                                    .buttonStyle(.plain)
                                }

                                ConversationRow(conversation: conversation)
                                    .contentShape(Rectangle())
                                    .onTapGesture {
                                        if isSelecting {
                                            toggleSelection(conversation.id)
                                        } else {
                                            selectedIndex = index
                                            onLoad?(conversation)
                                            dismiss()
                                        }
                                    }

                                Spacer()

                                if !isSelecting {
                                    Button {
                                        deleteConversation(conversation)
                                    } label: {
                                        Image(systemName: "trash")
                                            .foregroundStyle(.red)
                                            .font(.system(size: 16))
                                    }
                                    .buttonStyle(.plain)
                                    .help("Delete conversation")
                                }
                            }
                            .listRowBackground(
                                !isSelecting && index == selectedIndex
                                    ? Color.oaiAccent.opacity(0.15)
                                    : Color.clear
                            )
                            .id(conversation.id)
                            .swipeActions(edge: .trailing, allowsFullSwipe: false) {
                                Button(role: .destructive) {
                                    deleteConversation(conversation)
                                } label: {
                                    Label("Delete", systemImage: "trash")
                                }

                                Button {
                                    exportConversation(conversation)
                                } label: {
                                    Label("Export", systemImage: "square.and.arrow.up")
                                }
                                .tint(.blue)
                            }
                        }
                    }
                    .listStyle(.plain)
                    .onChange(of: selectedIndex) {
                        guard !filteredConversations.isEmpty else { return }
                        let clamped = min(selectedIndex, filteredConversations.count - 1)
                        withAnimation(.easeInOut(duration: 0.1)) {
                            proxy.scrollTo(filteredConversations[clamped].id, anchor: .center)
                        }
                    }
                }
            }

            Divider()

            // Bottom bar
            HStack {
                Text("↑↓ navigate  ↩ open")
                    .font(.system(size: 11))
                    .foregroundStyle(.tertiary)
                Spacer()
                Button("Done") { dismiss() }
                    .buttonStyle(.borderedProminent)
                    .controlSize(.regular)
            }
            .padding(.horizontal, 24)
            .padding(.vertical, 12)
        }
        .onAppear {
            loadConversations()
            searchFocused = true
        }
        .frame(minWidth: 700, idealWidth: 800, minHeight: 500, idealHeight: 600)
    }

    private func loadConversations() {
        do {
            conversations = try DatabaseService.shared.listConversations()
        } catch {
            Log.db.error("Failed to load conversations: \(error.localizedDescription)")
            conversations = []
        }
    }

    private func toggleSelection(_ id: UUID) {
        if selectedConversations.contains(id) {
            selectedConversations.remove(id)
        } else {
            selectedConversations.insert(id)
        }
    }

    private func deleteSelected() {
        for id in selectedConversations {
            do {
                let _ = try DatabaseService.shared.deleteConversation(id: id)
            } catch {
                Log.db.error("Failed to delete conversation: \(error.localizedDescription)")
            }
        }
        withAnimation {
            conversations.removeAll { selectedConversations.contains($0.id) }
            selectedConversations.removeAll()
            isSelecting = false
        }
        selectedIndex = 0
    }

    private func deleteConversation(_ conversation: Conversation) {
        do {
            let _ = try DatabaseService.shared.deleteConversation(id: conversation.id)
            withAnimation {
                conversations.removeAll { $0.id == conversation.id }
            }
            selectedIndex = min(selectedIndex, max(0, filteredConversations.count - 1))
        } catch {
            Log.db.error("Failed to delete conversation: \(error.localizedDescription)")
        }
    }

    private func performSemanticSearch() {
        guard !searchText.isEmpty else {
            semanticResults = []
            return
        }

        isSearching = true

        Task {
            do {
                guard let provider = EmbeddingService.shared.getSelectedProvider() else {
                    Log.api.warning("No embedding providers available - skipping semantic search")
                    await MainActor.run {
                        isSearching = false
                    }
                    return
                }

                let embedding = try await EmbeddingService.shared.generateEmbedding(
                    text: searchText,
                    provider: provider
                )

                let results = try DatabaseService.shared.searchConversationsBySemantic(
                    queryEmbedding: embedding,
                    limit: 20
                )

                await MainActor.run {
                    semanticResults = results.map { $0.0 }
                    selectedIndex = 0
                    isSearching = false
                    Log.ui.info("Semantic search found \(results.count) results using \(provider.displayName)")
                }
            } catch {
                await MainActor.run {
                    semanticResults = []
                    isSearching = false
                    Log.ui.error("Semantic search failed: \(error)")
                }
            }
        }
    }

    private func exportConversation(_ conversation: Conversation) {
        guard let (_, loadedMessages) = try? DatabaseService.shared.loadConversation(id: conversation.id),
              !loadedMessages.isEmpty else {
            return
        }
        let content = loadedMessages.map { msg in
            let header = msg.role == .user ? "**User**" : "**Assistant**"
            return "\(header)\n\n\(msg.content)"
        }.joined(separator: "\n\n---\n\n")

        let downloads = FileManager.default.urls(for: .downloadsDirectory, in: .userDomainMask).first
            ?? FileManager.default.temporaryDirectory
        let filename = conversation.name.replacingOccurrences(of: " ", with: "_") + ".md"
        let fileURL = downloads.appendingPathComponent(filename)
        try? content.write(to: fileURL, atomically: true, encoding: .utf8)
    }
}

struct ConversationRow: View {
    let conversation: Conversation

    private var formattedDate: String {
        let formatter = DateFormatter()
        formatter.dateFormat = "dd.MM.yyyy HH:mm"
        return formatter.string(from: conversation.updatedAt)
    }

    /// Strips the provider prefix from OpenRouter-style IDs (e.g. "anthropic/claude-3" → "claude-3")
    private var modelDisplayName: String? {
        guard let model = conversation.primaryModel, !model.isEmpty else { return nil }
        if let slash = model.lastIndex(of: "/") {
            return String(model[model.index(after: slash)...])
        }
        return model
    }

    var body: some View {
        VStack(alignment: .leading, spacing: 4) {
            Text(conversation.name)
                .font(.system(size: 15, weight: .semibold))
                .lineLimit(1)

            HStack(spacing: 6) {
                Label("\(conversation.messageCount)", systemImage: "message")
                    .font(.system(size: 12))

                Text("•")
                    .font(.system(size: 12))

                Text(formattedDate)
                    .font(.system(size: 12))

                if let model = modelDisplayName {
                    Text("•")
                        .font(.system(size: 12))
                    Text(model)
                        .font(.system(size: 12))
                        .lineLimit(1)
                        .truncationMode(.middle)
                }
            }
            .foregroundColor(.secondary)
        }
        .padding(.vertical, 5)
    }
}

#Preview {
    ConversationListView()
}