import AppKit
import SwiftUI

@MainActor
@Observable
final class TitleOptimizerViewModel {
    var draft = TitleDraft()
    var selectedTab: TitleOptimizerTab = .optimize
    var isOptimizing = false
    var errorMessage: String?
    var successMessage: String?
    var analysis: TitleAnalysis?
    var variants: [TitleVariant] = []
    var selectedVariantID: UUID?

    private let optimizationService: any TitleOptimizationServiceProtocol

    init(optimizationService: any TitleOptimizationServiceProtocol = MockTitleOptimizationService()) {
        self.optimizationService = optimizationService
    }

    var formattedSubreddit: String {
        let trimmed = draft.subreddit.trimmingCharacters(in: .whitespaces)
        guard !trimmed.isEmpty else { return "r/subreddit" }
        return trimmed.hasPrefix("r/") ? trimmed : "r/\(trimmed)"
    }

    var canOptimize: Bool {
        !draft.topic.trimmingCharacters(in: .whitespaces).isEmpty
            && !draft.subreddit.trimmingCharacters(in: .whitespaces).isEmpty
            && !draft.originalTitle.trimmingCharacters(in: .whitespaces).isEmpty
            && !isOptimizing
    }

    var activeTitle: String {
        if let selectedID = selectedVariantID,
           let variant = variants.first(where: { $0.id == selectedID }) {
            return variant.title
        }
        return draft.originalTitle
    }

    var bestVariant: TitleVariant? {
        variants.max(by: { $0.score < $1.score })
    }

    var previewDraft: PostDraft {
        PostDraft(
            postType: draft.postType,
            subreddit: draft.subreddit,
            topic: draft.topic,
            tone: draft.tone,
            title: activeTitle,
            isNSFW: draft.isNSFW,
            isSpoiler: draft.isSpoiler,
            isOC: draft.isOC,
            flair: draft.flair
        )
    }

    func selectPostType(_ type: RedditPostType) {
        draft.postType = type
        clearMessages()
    }

    func selectVariant(_ variant: TitleVariant) {
        selectedVariantID = variant.id
        clearMessages()
    }

    func applyVariant(_ variant: TitleVariant) {
        draft.originalTitle = variant.title
        selectedVariantID = variant.id
        successMessage = "Title applied."
        errorMessage = nil
    }

    func optimizeTitles() async {
        guard canOptimize else { return }

        isOptimizing = true
        errorMessage = nil
        successMessage = nil

        do {
            let result = try await optimizationService.optimizeTitles(from: draft)
            analysis = result.analysis
            variants = result.variants
            selectedVariantID = result.variants.first?.id
            successMessage = "Generated \(result.variants.count) title suggestions."
        } catch {
            errorMessage = error.localizedDescription
        }

        isOptimizing = false
    }

    func copyToClipboard() {
        let title = activeTitle.trimmingCharacters(in: .whitespaces)
        guard !title.isEmpty else { return }

        NSPasteboard.general.clearContents()
        NSPasteboard.general.setString(title, forType: .string)
        successMessage = "Copied to clipboard."
        errorMessage = nil
    }

    func resetDraft() {
        draft = TitleDraft()
        selectedTab = .optimize
        analysis = nil
        variants = []
        selectedVariantID = nil
        clearMessages()
    }

    func exportText() -> String {
        var lines: [String] = []
        lines.append("Subreddit: \(formattedSubreddit)")
        lines.append("Topic: \(draft.topic)")
        lines.append("Goal: \(draft.titleGoal.title)")
        lines.append("Tone: \(draft.tone.title)")
        lines.append("")
        lines.append("Original: \(draft.originalTitle)")

        if let analysis {
            lines.append("")
            lines.append("Analysis Score: \(analysis.overallScore)/100")
            lines.append("  Length: \(analysis.lengthScore)")
            lines.append("  Engagement: \(analysis.engagementScore)")
            lines.append("  Clarity: \(analysis.clarityScore)")
        }

        if !variants.isEmpty {
            lines.append("")
            lines.append("Suggestions:")
            for (index, variant) in variants.enumerated() {
                lines.append("\(index + 1). [\(variant.score)] \(variant.title)")
            }
        }

        return lines.joined(separator: "\n")
    }

    private func clearMessages() {
        errorMessage = nil
        successMessage = nil
    }
}