import SwiftUI

struct PromptEditorView: View {
    enum Mode {
        case add
        case edit(CustomPrompt)
        
        static func == (lhs: Mode, rhs: Mode) -> Bool {
            switch (lhs, rhs) {
            case (.add, .add):
                return true
            case let (.edit(prompt1), .edit(prompt2)):
                return prompt1.id == prompt2.id
            default:
                return false
            }
        }
    }
    
    let mode: Mode
    @Environment(\.dismiss) private var dismiss
    @EnvironmentObject private var enhancementService: AIEnhancementService
    var onDismiss: (() -> Void)?
    @State private var title: String
    @State private var promptText: String
    @State private var selectedIcon: PromptIcon
    @State private var description: String
    @State private var triggerWords: [String]
    @State private var useSystemInstructions: Bool
    @State private var showingIconPicker = false
    
    private var isEditingPredefinedPrompt: Bool {
        if case .edit(let prompt) = mode {
            return prompt.isPredefined
        }
        return false
    }
    
    init(mode: Mode, onDismiss: (() -> Void)? = nil) {
        self.mode = mode
        self.onDismiss = onDismiss
        switch mode {
        case .add:
            _title = State(initialValue: "")
            _promptText = State(initialValue: "")
            _selectedIcon = State(initialValue: "doc.text.fill")
            _description = State(initialValue: "")
            _triggerWords = State(initialValue: [])
            _useSystemInstructions = State(initialValue: true)
        case .edit(let prompt):
            _title = State(initialValue: prompt.title)
            _promptText = State(initialValue: prompt.promptText)
            _selectedIcon = State(initialValue: prompt.icon)
            _description = State(initialValue: prompt.description ?? "")
            _triggerWords = State(initialValue: prompt.triggerWords)
            _useSystemInstructions = State(initialValue: prompt.useSystemInstructions)
        }
    }
    
    var body: some View {
        VStack(spacing: 0) {
            HStack(spacing: 12) {
                Text(isEditingPredefinedPrompt ? "Edit Trigger Words" : (mode == .add ? "New Prompt" : "Edit Prompt"))
                    .font(.headline)
                    .fontWeight(.semibold)
                    .foregroundColor(.primary)
                
                Spacer()
                
                Button(action: {
                    if let onDismiss = onDismiss {
                        onDismiss()
                    } else {
                        dismiss()
                    }
                }) {
                    Image(systemName: "xmark")
                        .font(.system(size: 14, weight: .medium))
                        .foregroundColor(.secondary)
                        .padding(6)
                        .background(Color.secondary.opacity(0.1))
                        .clipShape(Circle())
                }
                .buttonStyle(.plain)
                .help("Close")
            }
            .padding(.horizontal, 20)
            .padding(.vertical, 16)
            .background(Color(NSColor.windowBackgroundColor))
            .overlay(
                Divider().opacity(0.5), alignment: .bottom
            )
            
            ScrollView {
                VStack(spacing: 24) {
                    if isEditingPredefinedPrompt {
                        VStack(alignment: .leading, spacing: 16) {
                            Text("Editing: \(title)")
                                .font(.title3)
                                .fontWeight(.medium)
                                .foregroundColor(.primary)
                            
                            Text("You can only customize the trigger words for system prompts.")
                                .font(.subheadline)
                                .foregroundColor(.secondary)
                            
                            TriggerWordsEditor(triggerWords: $triggerWords)
                        }
                        .padding(.horizontal, 20)
                        .padding(.vertical, 20)
                        
                    } else {
                        VStack(spacing: 24) {
                            HStack(alignment: .top, spacing: 16) {
                                Button(action: { showingIconPicker = true }) {
                                    Image(systemName: selectedIcon)
                                        .font(.system(size: 24))
                                        .foregroundColor(.primary)
                                        .frame(width: 56, height: 56)
                                        .background(Color(NSColor.controlBackgroundColor))
                                        .cornerRadius(10)
                                        .overlay(
                                            RoundedRectangle(cornerRadius: 10)
                                                .stroke(Color.secondary.opacity(0.2), lineWidth: 1)
                                        )
                                }
                                .buttonStyle(.plain)
                                .popover(isPresented: $showingIconPicker, arrowEdge: .bottom) {
                                    IconPickerPopover(selectedIcon: $selectedIcon, isPresented: $showingIconPicker)
                                }
                                
                                VStack(alignment: .leading, spacing: 6) {
                                    Text("Title")
                                        .font(.subheadline)
                                        .foregroundColor(.secondary)
                                    
                                    TextField("Prompt Name", text: $title)
                                        .textFieldStyle(.plain)
                                        .font(.system(size: 14))
                                        .padding(8)
                                        .background(
                                            RoundedRectangle(cornerRadius: 6)
                                                .stroke(Color.secondary.opacity(0.2), lineWidth: 1)
                                                .background(Color(NSColor.controlBackgroundColor).cornerRadius(6))
                                        )
                                }
                            }
                            
                            VStack(alignment: .leading, spacing: 6) {
                                Text("Description")
                                    .font(.subheadline)
                                    .foregroundColor(.secondary)
                                
                                TextField("Brief description of what this prompt does", text: $description)
                                    .textFieldStyle(.plain)
                                    .font(.system(size: 13))
                                    .padding(8)
                                    .background(
                                        RoundedRectangle(cornerRadius: 6)
                                            .stroke(Color.secondary.opacity(0.2), lineWidth: 1)
                                            .background(Color(NSColor.controlBackgroundColor).cornerRadius(6))
                                    )
                            }
                            
                            Divider().padding(.vertical, 4)
                            
                            VStack(alignment: .leading, spacing: 8) {
                                HStack(spacing: 6) {
                                    Text("Instructions")
                                        .font(.headline)
                                        .foregroundColor(.primary)
                                    
                                    InfoTip(
                                        title: "Instructions",
                                        message: "Define how AI should process the text."
                                    )
                                }
                                
                                ZStack(alignment: .topLeading) {
                                    TextEditor(text: $promptText)
                                        .font(.system(.body, design: .monospaced))
                                        .frame(minHeight: 180)
                                        .padding(8)
                                        .background(Color(NSColor.controlBackgroundColor))
                                        .cornerRadius(6)
                                        .overlay(
                                            RoundedRectangle(cornerRadius: 6)
                                                .stroke(Color.secondary.opacity(0.2), lineWidth: 1)
                                        )
                                    
                                    if promptText.isEmpty {
                                        Text("Enter your custom prompt instructions here...")
                                            .font(.system(.body, design: .monospaced))
                                            .foregroundColor(.secondary.opacity(0.5))
                                            .padding(.horizontal, 12)
                                            .padding(.vertical, 12)
                                            .allowsHitTesting(false                                        )
                                    }
                                }
                                
                                if !isEditingPredefinedPrompt {
                                    HStack(spacing: 8) {
                                        Toggle("Use System Template", isOn: $useSystemInstructions)
                                            .toggleStyle(.switch)
                                            .controlSize(.small)
                                        
                                        InfoTip(
                                            title: "System Instructions",
                                            message: "If enabled, your instructions are combined with a general-purpose template to improve transcription quality.\n\nDisable for full control over the AI's system prompt (for advanced users)."
                                        )
                                    }
                                    .padding(.top, 4)
                                }
                            }
                            
                            Divider().padding(.vertical, 4)
                            
                            TriggerWordsEditor(triggerWords: $triggerWords)
                            
                            if case .add = mode, !isEditingPredefinedPrompt {
                                HStack {
                                    Menu {
                                        ForEach(PromptTemplates.all, id: \.title) { template in
                                            Button {
                                                title = template.title
                                                promptText = template.promptText
                                                selectedIcon = template.icon
                                                description = template.description
                                            } label: {
                                                HStack {
                                                    Text(template.title)
                                                    Spacer()
                                                    Image(systemName: template.icon)
                                                }
                                            }
                                        }
                                    } label: {
                                        HStack(spacing: 6) {
                                            Image(systemName: "sparkles")
                                                .foregroundColor(.accentColor)
                                            Text("Start with Template")
                                                .foregroundColor(.primary)
                                            Image(systemName: "chevron.down")
                                                .font(.caption)
                                                .foregroundColor(.secondary)
                                        }
                                        .padding(.vertical, 6)
                                        .padding(.horizontal, 10)
                                        .background(Color(NSColor.controlBackgroundColor))
                                        .cornerRadius(6)
                                        .overlay(
                                            RoundedRectangle(cornerRadius: 6)
                                                .stroke(Color.secondary.opacity(0.15), lineWidth: 1)
                                        )
                                    }
                                    .menuStyle(.borderlessButton)
                                    .fixedSize()
                                    
                                    Spacer()
                                }
                            }
                        }
                        .padding(.horizontal, 20)
                        .padding(.vertical, 20)
                    }
                }
            }
            
            VStack(spacing: 0) {
                Divider()
                HStack {
                    Button("Cancel") {
                        if let onDismiss = onDismiss {
                            onDismiss()
                        } else {
                            dismiss()
                        }
                    }
                    .keyboardShortcut(.escape, modifiers: [])
                    .buttonStyle(.plain)
                    .foregroundColor(.secondary)
                    
                    Spacer()
                    
                    Button {
                        save()
                        if let onDismiss = onDismiss {
                            onDismiss()
                        } else {
                            dismiss()
                        }
                    } label: {
                        Text("Save Changes")
                            .frame(minWidth: 100)
                    }
                    .buttonStyle(.borderedProminent)
                    .disabled(isEditingPredefinedPrompt ? false : (title.isEmpty || promptText.isEmpty))
                    .keyboardShortcut(.return, modifiers: .command)
                }
                .padding(.horizontal, 20)
                .padding(.vertical, 16)
                .background(Color(NSColor.windowBackgroundColor))
            }
        }
        .frame(minWidth: 400, minHeight: 500)
        .background(Color(NSColor.windowBackgroundColor))
    }
    
    private func save() {
        switch mode {
        case .add:
            enhancementService.addPrompt(
                title: title,
                promptText: promptText,
                icon: selectedIcon,
                description: description.isEmpty ? nil : description,
                triggerWords: triggerWords,
                useSystemInstructions: useSystemInstructions
            )
        case .edit(let prompt):
            let updatedPrompt = CustomPrompt(
                id: prompt.id,
                title: prompt.isPredefined ? prompt.title : title,
                promptText: prompt.isPredefined ? prompt.promptText : promptText,
                isActive: prompt.isActive,
                icon: prompt.isPredefined ? prompt.icon : selectedIcon,
                description: prompt.isPredefined ? prompt.description : (description.isEmpty ? nil : description),
                isPredefined: prompt.isPredefined,
                triggerWords: triggerWords,
                useSystemInstructions: useSystemInstructions
            )
            enhancementService.updatePrompt(updatedPrompt)
        }
    }
}

// MARK: - Trigger Words Editor
struct TriggerWordsEditor: View {
    @Binding var triggerWords: [String]
    @State private var newTriggerWord: String = ""
    
    var body: some View {
        VStack(alignment: .leading, spacing: 8) {
            HStack(spacing: 6) {
                Text("Trigger Words")
                    .font(.subheadline)
                    .foregroundColor(.secondary)
                
                InfoTip(
                    title: "Trigger Words",
                    message: "Add multiple words that can activate this prompt."
                )
            }
            
            HStack {
                TextField("Add trigger word (e.g. 'summarize')", text: $newTriggerWord)
                    .textFieldStyle(.plain)
                    .font(.system(size: 13))
                    .padding(6)
                    .background(
                        RoundedRectangle(cornerRadius: 6)
                            .stroke(Color.secondary.opacity(0.2), lineWidth: 1)
                            .background(Color(NSColor.controlBackgroundColor).cornerRadius(6))
                    )
                    .onSubmit {
                        addTriggerWord()
                    }
                
                Button(action: { addTriggerWord() }) {
                    Image(systemName: "plus")
                        .font(.system(size: 12, weight: .bold))
                        .frame(width: 26, height: 26)
                        .background(Color.accentColor.opacity(0.1))
                        .foregroundColor(.accentColor)
                        .clipShape(RoundedRectangle(cornerRadius: 6))
                }
                .buttonStyle(.plain)
                .disabled(newTriggerWord.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty)
            }
            
            if !triggerWords.isEmpty {
                TagLayout(alignment: .leading, spacing: 6) {
                    ForEach(triggerWords, id: \.self) { word in
                        TriggerWordItemView(word: word) {
                            triggerWords.removeAll { $0 == word }
                        }
                    }
                }
                .padding(.top, 4)
            } else {
                Text("No trigger words added")
                    .font(.caption)
                    .foregroundColor(.secondary.opacity(0.7))
                    .italic()
                    .padding(.top, 2)
            }
        }
    }
    
    private func addTriggerWord() {
        let trimmedWord = newTriggerWord.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !trimmedWord.isEmpty else { return }
        
        let lowerCaseWord = trimmedWord.lowercased()
        guard !triggerWords.contains(where: { $0.lowercased() == lowerCaseWord }) else { return }
        
        triggerWords.append(trimmedWord)
        newTriggerWord = ""
    }
}

// MARK: - Trigger Word Item
struct TriggerWordItemView: View {
    let word: String
    let onDelete: () -> Void
    @State private var isHovered = false
    
    var body: some View {
        HStack(spacing: 4) {
                Text(word)
                    .font(.system(size: 12))
                    .lineLimit(1)
                    .truncationMode(.tail)
                    .frame(maxWidth: 120, alignment: .leading)
                    .foregroundColor(.primary)
            
            Button(action: onDelete) {
                Image(systemName: "xmark")
                    .font(.system(size: 10, weight: .bold))
                    .foregroundColor(.secondary)
            }
            .buttonStyle(.plain)
            .padding(.leading, 2)
        }
        .padding(.horizontal, 8)
        .padding(.vertical, 4)
        .background(Color(NSColor.controlBackgroundColor))
        .cornerRadius(4)
        .overlay(
            RoundedRectangle(cornerRadius: 4)
                .stroke(Color.secondary.opacity(0.2), lineWidth: 1)
        )
    }
}

// MARK: - Tag Layout
struct TagLayout: Layout {
    var alignment: Alignment = .leading
    var spacing: CGFloat = 8
    
    func sizeThatFits(proposal: ProposedViewSize, subviews: Subviews, cache: inout ()) -> CGSize {
        let maxWidth = proposal.width ?? .infinity
        var height: CGFloat = 0
        var currentRowWidth: CGFloat = 0
        
        for subview in subviews {
            let size = subview.sizeThatFits(.unspecified)
            
            if currentRowWidth + size.width > maxWidth {
                // New row
                height += size.height + spacing
                currentRowWidth = size.width + spacing
            } else {
                // Same row
                currentRowWidth += size.width + spacing
            }
            
            if height == 0 {
                height = size.height
            }
        }
        
        return CGSize(width: maxWidth, height: height)
    }
    
    func placeSubviews(in bounds: CGRect, proposal: ProposedViewSize, subviews: Subviews, cache: inout ()) {
        var x = bounds.minX
        var y = bounds.minY
        let maxHeight = subviews.map { $0.sizeThatFits(.unspecified).height }.max() ?? 0
        
        for subview in subviews {
            let size = subview.sizeThatFits(.unspecified)
            
            if x + size.width > bounds.maxX {
                x = bounds.minX
                y += maxHeight + spacing
            }
            
            subview.place(at: CGPoint(x: x, y: y), proposal: ProposedViewSize(size))
            x += size.width + spacing
        }
    }
}

// MARK: - Icon Picker
struct IconPickerPopover: View {
    @Binding var selectedIcon: PromptIcon
    @Binding var isPresented: Bool
    
    var body: some View {
        let columns = [
            GridItem(.adaptive(minimum: 45, maximum: 52), spacing: 14)
        ]
        
        ScrollView {
            LazyVGrid(columns: columns, spacing: 14) {
                ForEach(PromptIcon.allCases, id: \.self) { icon in
                    Button(action: {
                        withAnimation(.spring(response: 0.2, dampingFraction: 0.7)) {
                            selectedIcon = icon
                            isPresented = false
                        }
                    }) {
                        ZStack {
                            RoundedRectangle(cornerRadius: 12)
                                .fill(selectedIcon == icon ? Color(NSColor.windowBackgroundColor) : Color(NSColor.controlBackgroundColor))
                                .frame(width: 52, height: 52)
                                .overlay(
                                    RoundedRectangle(cornerRadius: 12)
                                        .stroke(selectedIcon == icon ? Color(NSColor.separatorColor) : Color.secondary.opacity(0.2), lineWidth: selectedIcon == icon ? 2 : 1)
                                )
                            
                            Image(systemName: icon)
                                .font(.system(size: 24, weight: .medium))
                                .foregroundColor(.primary)
                        }
                        .scaleEffect(selectedIcon == icon ? 1.1 : 1.0)
                        .animation(.spring(response: 0.2, dampingFraction: 0.7), value: selectedIcon == icon)
                    }
                    .buttonStyle(.plain)
                }
            }
            .padding(20)
        }
        .frame(width: 400, height: 400)
    }
}