//
//  ConversationExporter.swift
//  Zyquo Cloud
//
//  Author: Simon-Pierre Boucher
//  Mail: contact@spboucher.ai
//
//  Conversation export: Markdown text and PDF (rendered via NSPrintOperation-
//  compatible attributed text into a PDF context).
//

import AppKit
import UniformTypeIdentifiers

enum ConversationExporter {
    // MARK: - Markdown

    static func markdown(for conversation: Conversation) -> String {
        var lines: [String] = []
        lines.append("# \(conversation.title)")
        lines.append("")
        lines.append("*Exported from Zyquo Cloud — \(conversation.provider.displayName) · \(conversation.modelID)*")
        if let system = conversation.systemPrompt, !system.isEmpty {
            lines.append("")
            lines.append("> **System:** \(system)")
        }
        for message in conversation.messages {
            lines.append("")
            switch message.role {
            case .user:
                lines.append("## 🧑 You")
            case .assistant:
                let model = message.modelID ?? conversation.modelID
                lines.append("## ☁️ Assistant (\(model))")
            case .system:
                lines.append("## System")
            }
            lines.append("")
            if let reasoning = message.reasoning, !reasoning.isEmpty {
                lines.append("<details><summary>Thinking</summary>")
                lines.append("")
                lines.append(reasoning)
                lines.append("")
                lines.append("</details>")
                lines.append("")
            }
            lines.append(message.text)
            if !message.citations.isEmpty {
                lines.append("")
                lines.append("**Sources:**")
                for citation in message.citations {
                    lines.append("\(citation.index). [\(citation.title ?? citation.url.absoluteString)](\(citation.url.absoluteString))")
                }
            }
        }
        lines.append("")
        return lines.joined(separator: "\n")
    }

    // MARK: - PDF

    static func pdfData(for conversation: Conversation) -> Data? {
        let text = markdown(for: conversation)
        let attributed = NSMutableAttributedString(
            string: text,
            attributes: [
                .font: NSFont.systemFont(ofSize: 11),
                .foregroundColor: NSColor.textColor,
            ]
        )
        let pageRect = CGRect(x: 0, y: 0, width: 612, height: 792) // US Letter
        let inset: CGFloat = 48
        let data = NSMutableData()
        guard let consumer = CGDataConsumer(data: data as CFMutableData),
              var mediaBox = Optional(pageRect),
              let context = CGContext(consumer: consumer, mediaBox: &mediaBox, nil)
        else { return nil }

        let framesetter = CTFramesetterCreateWithAttributedString(attributed)
        var location = 0
        while location < attributed.length {
            context.beginPDFPage(nil)
            let path = CGPath(
                rect: pageRect.insetBy(dx: inset, dy: inset), transform: nil
            )
            let frame = CTFramesetterCreateFrame(
                framesetter, CFRange(location: location, length: 0), path, nil
            )
            CTFrameDraw(frame, context)
            let visible = CTFrameGetVisibleStringRange(frame)
            location += max(visible.length, 1)
            context.endPDFPage()
        }
        context.closePDF()
        return data as Data
    }

    // MARK: - Save panel

    @MainActor
    static func presentSavePanel(for conversation: Conversation) {
        let panel = NSSavePanel()
        panel.allowedContentTypes = [
            UTType(filenameExtension: "md") ?? .plainText,
            .pdf,
        ]
        panel.nameFieldStringValue = conversation.title
            .replacingOccurrences(of: "/", with: "-")
        panel.title = "Export Conversation"
        panel.begin { response in
            guard response == .OK, let url = panel.url else { return }
            if url.pathExtension.lowercased() == "pdf" {
                if let data = pdfData(for: conversation) {
                    try? data.write(to: url)
                }
            } else {
                let text = markdown(for: conversation)
                try? text.data(using: .utf8)?.write(to: url)
            }
        }
    }
}