//
//  PersistenceService.swift
//  Zyquo Local
//
//  Author: Simon-Pierre Boucher
//  Mail: contact@spboucher.ai
//

import Foundation

/// Conversations, personas and settings persisted as JSON under
/// ~/Library/Application Support/ZyquoLocal/.
enum PersistenceService {
    static var appSupportDirectory: URL {
        let base = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)[0]
        let dir = base.appendingPathComponent("ZyquoLocal")
        try? FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)
        return dir
    }

    private static var conversationsDirectory: URL {
        let dir = appSupportDirectory.appendingPathComponent("Conversations")
        try? FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)
        return dir
    }

    private static let encoder: JSONEncoder = {
        let e = JSONEncoder()
        e.dateEncodingStrategy = .iso8601
        e.outputFormatting = [.sortedKeys]
        return e
    }()

    private static let decoder: JSONDecoder = {
        let d = JSONDecoder()
        d.dateDecodingStrategy = .iso8601
        return d
    }()

    // MARK: - Conversations (one JSON file per conversation)

    static func loadConversations() -> [Conversation] {
        let files = (try? FileManager.default.contentsOfDirectory(
            at: conversationsDirectory, includingPropertiesForKeys: nil)) ?? []
        return files
            .filter { $0.pathExtension == "json" }
            .compactMap { url in
                guard let data = try? Data(contentsOf: url) else { return nil }
                return try? decoder.decode(Conversation.self, from: data)
            }
            .sorted { $0.updatedAt > $1.updatedAt }
    }

    static func save(_ conversation: Conversation) {
        let url = conversationsDirectory.appendingPathComponent("\(conversation.id.uuidString).json")
        try? encoder.encode(conversation).write(to: url, options: .atomic)
    }

    static func delete(conversationID: UUID) {
        let url = conversationsDirectory.appendingPathComponent("\(conversationID.uuidString).json")
        try? FileManager.default.removeItem(at: url)
    }

    // MARK: - Generic single-document storage (settings, personas, prompts)

    static func loadDocument<T: Decodable>(_ type: T.Type, named name: String) -> T? {
        let url = appSupportDirectory.appendingPathComponent("\(name).json")
        guard let data = try? Data(contentsOf: url) else { return nil }
        return try? decoder.decode(T.self, from: data)
    }

    static func saveDocument<T: Encodable>(_ value: T, named name: String) {
        let url = appSupportDirectory.appendingPathComponent("\(name).json")
        try? encoder.encode(value).write(to: url, options: .atomic)
    }
}