/**
 * Millisa AI Client for iOS (Swift)
 * ─────────────────────────────────────────────────────────────────────────────
 * Compatible with iOS 15.0+, macOS 12.0+, Swift 5.5+ (Modern Async/Await & Concurrency)
 */

import Foundation

public final class MillisaClient {
    private let apiKey: String
    private let baseURL: URL

    public init(apiKey: String, baseURL: String = "https://millisa.codly.in/api/v1") {
        self.apiKey = apiKey
        self.baseURL = URL(string: baseURL)!
    }

    /**
     * Send a single prompt query to Millisa AI Agent
     */
    public func queryAgent(prompt: String, model: String = "millisa-auto") async throws -> String {
        let endpoint = baseURL.appendingPathComponent("agent/query")
        var request = URLRequest(url: endpoint)
        request.httpMethod = "POST"
        request.addValue("Bearer \(apiKey)", forHTTPHeaderField: "Authorization")
        request.addValue("application/json", forHTTPHeaderField: "Content-Type")

        let body: [String: Any] = [
            "prompt": prompt,
            "model": model
        ]
        request.httpBody = try JSONSerialization.data(withJSONObject: body)

        let (data, response) = try await URLSession.shared.data(for: request)

        guard let httpResponse = response as? HTTPURLResponse else {
            throw URLError(.badServerResponse)
        }

        guard httpResponse.statusCode == 200 else {
            let errorJson = (try? JSONSerialization.jsonObject(with: data) as? [String: Any])?["error"] as? [String: Any]
            let message = errorJson?["message"] as? String ?? "HTTP Error \(httpResponse.statusCode)"
            throw NSError(domain: "MillisaError", code: httpResponse.statusCode, userInfo: [NSLocalizedDescriptionKey: message])
        }

        guard let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
              let reply = json["response"] as? String else {
            throw URLError(.cannotParseResponse)
        }

        return reply
    }

    /**
     * Multi-turn chat completion (OpenAI-compatible)
     */
    public func chatCompletion(
        messages: [[String: String]], // [["role": "user", "content": "..."]]
        model: String = "millisa-auto"
    ) async throws -> String {
        let endpoint = baseURL.appendingPathComponent("chat/completions")
        var request = URLRequest(url: endpoint)
        request.httpMethod = "POST"
        request.addValue("Bearer \(apiKey)", forHTTPHeaderField: "Authorization")
        request.addValue("application/json", forHTTPHeaderField: "Content-Type")

        let body: [String: Any] = [
            "model": model,
            "messages": messages
        ]
        request.httpBody = try JSONSerialization.data(withJSONObject: body)

        let (data, response) = try await URLSession.shared.data(for: request)

        guard let httpResponse = response as? HTTPURLResponse, httpResponse.statusCode == 200 else {
            throw URLError(.badServerResponse)
        }

        guard let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
              let choices = json["choices"] as? [[String: Any]],
              let message = choices.first?["message"] as? [String: Any],
              let content = message["content"] as? String else {
            throw URLError(.cannotParseResponse)
        }

        return content
    }
}

// ─────────────────────────────────────────────────────────────────────────────
// Usage Example in SwiftUI / iOS:
// ─────────────────────────────────────────────────────────────────────────────
/*
let millisa = MillisaClient(apiKey: "mls_live_YOUR_MILLISA_API_KEY")

Task {
    do {
        let reply = try await millisa.queryAgent(prompt: "Hello Millisa, recommend best architecture for iOS apps.")
        print("Millisa replied:\n\(reply)")
    } catch {
        print("Error: \(error.localizedDescription)")
    }
}
*/