//
//  PersistenceService.swift
//  Zyquo Cloud
//
//  Author: Simon-Pierre Boucher
//  Mail: contact@spboucher.ai
//
//  JSON persistence in ~/Library/Application Support/ZyquoCloud/:
//    Conversations/<uuid>.json   one file per conversation
//    personas.json, templates.json, favorites.json, settings.json
//

import Foundation

struct PersistenceService {
    static let shared = PersistenceService()

    let rootDirectory: URL
    var conversationsDirectory: URL { rootDirectory.appendingPathComponent("Conversations") }

    private let encoder: JSONEncoder
    private let decoder: JSONDecoder

    init(rootDirectory: URL? = nil) {
        let base = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)[0]
        self.rootDirectory = rootDirectory ?? base.appendingPathComponent("ZyquoCloud")
        encoder = JSONEncoder()
        encoder.outputFormatting = [.prettyPrinted, .sortedKeys]
        encoder.dateEncodingStrategy = .iso8601
        decoder = JSONDecoder()
        decoder.dateDecodingStrategy = .iso8601
        try? FileManager.default.createDirectory(at: conversationsDirectory, withIntermediateDirectories: true)
    }

    // MARK: - Conversations

    func loadConversations() -> [Conversation] {
        guard let files = try? FileManager.default.contentsOfDirectory(
            at: conversationsDirectory, includingPropertiesForKeys: nil
        ) else { return [] }
        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 }
    }

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

    func delete(_ conversation: Conversation) {
        let url = conversationsDirectory.appendingPathComponent("\(conversation.id.uuidString).json")
        try? FileManager.default.removeItem(at: url)
    }

    // MARK: - Generic documents (personas, templates, settings…)

    func load<T: Decodable>(_ type: T.Type, from fileName: String) -> T? {
        let url = rootDirectory.appendingPathComponent(fileName)
        guard let data = try? Data(contentsOf: url) else { return nil }
        return try? decoder.decode(type, from: data)
    }

    func save<T: Encodable>(_ value: T, to fileName: String) {
        let url = rootDirectory.appendingPathComponent(fileName)
        guard let data = try? encoder.encode(value) else { return }
        try? data.write(to: url, options: .atomic)
    }
}