//
//  OllamaProvider.swift
//  oAI
//
//  Ollama local AI provider with JSON-lines streaming
//

import Foundation
import os

class OllamaProvider: AIProvider {
    let name = "Ollama"
    let capabilities = ProviderCapabilities(
        supportsStreaming: true,
        supportsVision: false,
        supportsTools: false,
        supportsOnlineSearch: false,
        maxContextLength: nil
    )

    private let baseURL: String
    private let session: URLSession

    init(baseURL: String = "http://localhost:11434") {
        self.baseURL = baseURL.hasSuffix("/") ? String(baseURL.dropLast()) : baseURL
        let config = URLSessionConfiguration.default
        config.timeoutIntervalForRequest = 120
        config.timeoutIntervalForResource = 600
        self.session = URLSession(configuration: config)
    }

    // MARK: - Models

    func listModels() async throws -> [ModelInfo] {
        Log.api.info("Fetching model list from Ollama at \(self.baseURL)")
        let url = URL(string: "\(baseURL)/api/tags")!
        var request = URLRequest(url: url)
        request.timeoutInterval = 5

        let data: Data
        let response: URLResponse
        do {
            (data, response) = try await session.data(for: request)
        } catch {
            Log.api.warning("Cannot connect to Ollama at \(self.baseURL). Is Ollama running?")
            throw ProviderError.unknown("Cannot connect to Ollama at \(baseURL). Is Ollama running? Start it with: ollama serve")
        }

        guard let httpResponse = response as? HTTPURLResponse, httpResponse.statusCode == 200 else {
            throw ProviderError.unknown("Ollama returned an error. Is it running?")
        }

        guard let json = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
              let modelsArray = json["models"] as? [[String: Any]] else {
            return []
        }

        return modelsArray.compactMap { model -> ModelInfo? in
            guard let name = model["name"] as? String else { return nil }
            let sizeBytes = model["size"] as? Int64 ?? 0
            let sizeGB = String(format: "%.1f GB", Double(sizeBytes) / 1_073_741_824)

            return ModelInfo(
                id: name,
                name: name,
                description: "Local model (\(sizeGB))",
                contextLength: 0,
                pricing: .init(prompt: 0, completion: 0),
                capabilities: .init(vision: false, tools: false, online: false)
            )
        }
    }

    func getModel(_ id: String) async throws -> ModelInfo? {
        let models = try await listModels()
        return models.first { $0.id == id }
    }

    // MARK: - Chat Completion

    func chat(request: ChatRequest) async throws -> ChatResponse {
        Log.api.info("Ollama chat request: model=\(request.model), messages=\(request.messages.count)")
        let url = URL(string: "\(baseURL)/api/chat")!
        let body = buildRequestBody(from: request, stream: false)
        let bodyData = try JSONSerialization.data(withJSONObject: body)

        var urlRequest = URLRequest(url: url)
        urlRequest.httpMethod = "POST"
        urlRequest.addValue("application/json", forHTTPHeaderField: "Content-Type")
        urlRequest.httpBody = bodyData

        let (data, response) = try await session.data(for: urlRequest)

        guard let httpResponse = response as? HTTPURLResponse else {
            Log.api.error("Ollama chat: invalid response (not HTTP)")
            throw ProviderError.invalidResponse
        }
        guard httpResponse.statusCode == 200 else {
            if let errorObj = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
               let errorMsg = errorObj["error"] as? String {
                Log.api.error("Ollama chat HTTP \(httpResponse.statusCode): \(errorMsg)")
                throw ProviderError.unknown(errorMsg)
            }
            Log.api.error("Ollama chat HTTP \(httpResponse.statusCode)")
            throw ProviderError.unknown("Ollama HTTP \(httpResponse.statusCode)")
        }

        guard let json = try? JSONSerialization.jsonObject(with: data) as? [String: Any] else {
            throw ProviderError.invalidResponse
        }

        return parseOllamaResponse(json, model: request.model)
    }

    // MARK: - Chat with raw tool messages

    func chatWithToolMessages(model: String, messages: [[String: Any]], tools: [Tool]?, maxTokens: Int?, temperature: Double?) async throws -> ChatResponse {
        // Ollama doesn't support tool calls natively — just send messages as plain chat
        let url = URL(string: "\(baseURL)/api/chat")!

        // Convert messages, stripping tool-specific fields
        var ollamaMessages: [[String: Any]] = []
        for msg in messages {
            let role = msg["role"] as? String ?? "user"
            let content = msg["content"] as? String ?? ""

            if role == "tool" {
                // Convert tool results to assistant context
                let toolName = msg["name"] as? String ?? "tool"
                ollamaMessages.append(["role": "user", "content": "[\(toolName) result]: \(content)"])
            } else if role == "assistant" {
                // Strip tool_calls, just keep content
                if let tc = msg["tool_calls"] as? [[String: Any]], !tc.isEmpty {
                    let toolNames = tc.compactMap { ($0["function"] as? [String: Any])?["name"] as? String }
                    let text = (msg["content"] as? String) ?? ""
                    let combined = text.isEmpty ? "Calling: \(toolNames.joined(separator: ", "))" : text
                    ollamaMessages.append(["role": "assistant", "content": combined])
                } else {
                    ollamaMessages.append(["role": "assistant", "content": content])
                }
            } else {
                ollamaMessages.append(["role": role, "content": content])
            }
        }

        var body: [String: Any] = [
            "model": model,
            "messages": ollamaMessages,
            "stream": false
        ]
        var options: [String: Any] = [:]
        if let maxTokens = maxTokens { options["num_predict"] = maxTokens }
        if let temperature = temperature { options["temperature"] = temperature }
        if !options.isEmpty { body["options"] = options }

        let bodyData = try JSONSerialization.data(withJSONObject: body)

        var urlRequest = URLRequest(url: url)
        urlRequest.httpMethod = "POST"
        urlRequest.addValue("application/json", forHTTPHeaderField: "Content-Type")
        urlRequest.httpBody = bodyData

        let (data, response) = try await session.data(for: urlRequest)

        guard let httpResponse = response as? HTTPURLResponse, httpResponse.statusCode == 200 else {
            throw ProviderError.unknown("Ollama error")
        }

        guard let json = try? JSONSerialization.jsonObject(with: data) as? [String: Any] else {
            throw ProviderError.invalidResponse
        }

        return parseOllamaResponse(json, model: model)
    }

    // MARK: - Streaming Chat

    func streamChat(request: ChatRequest) -> AsyncThrowingStream<StreamChunk, Error> {
        Log.api.info("Ollama stream request: model=\(request.model), messages=\(request.messages.count)")
        return AsyncThrowingStream { continuation in
            Task {
                do {
                    let url = URL(string: "\(baseURL)/api/chat")!
                    let body = buildRequestBody(from: request, stream: true)
                    let bodyData = try JSONSerialization.data(withJSONObject: body)

                    var urlRequest = URLRequest(url: url)
                    urlRequest.httpMethod = "POST"
                    urlRequest.addValue("application/json", forHTTPHeaderField: "Content-Type")
                    urlRequest.httpBody = bodyData

                    let (bytes, response) = try await session.bytes(for: urlRequest)

                    guard let httpResponse = response as? HTTPURLResponse else {
                        Log.api.error("Ollama stream: invalid response (not HTTP)")
                        continuation.finish(throwing: ProviderError.invalidResponse)
                        return
                    }
                    guard httpResponse.statusCode == 200 else {
                        Log.api.error("Ollama stream HTTP \(httpResponse.statusCode)")
                        continuation.finish(throwing: ProviderError.unknown("Ollama HTTP \(httpResponse.statusCode)"))
                        return
                    }

                    // Ollama streams JSON lines (one complete JSON object per line)
                    for try await line in bytes.lines {
                        guard !line.isEmpty,
                              let lineData = line.data(using: .utf8),
                              let json = try? JSONSerialization.jsonObject(with: lineData) as? [String: Any] else {
                            continue
                        }

                        let done = json["done"] as? Bool ?? false
                        let message = json["message"] as? [String: Any]
                        let content = message?["content"] as? String

                        if done {
                            // Final chunk has usage stats
                            let promptTokens = json["prompt_eval_count"] as? Int ?? 0
                            let completionTokens = json["eval_count"] as? Int ?? 0
                            continuation.yield(StreamChunk(
                                id: "",
                                model: request.model,
                                delta: .init(content: content, role: nil, images: nil),
                                finishReason: "stop",
                                usage: ChatResponse.Usage(
                                    promptTokens: promptTokens,
                                    completionTokens: completionTokens,
                                    totalTokens: promptTokens + completionTokens
                                )
                            ))
                            continuation.finish()
                            return
                        } else if let content = content {
                            continuation.yield(StreamChunk(
                                id: "",
                                model: request.model,
                                delta: .init(content: content, role: nil, images: nil),
                                finishReason: nil,
                                usage: nil
                            ))
                        }
                    }

                    continuation.finish()
                } catch {
                    continuation.finish(throwing: error)
                }
            }
        }
    }

    // MARK: - Credits

    func getCredits() async throws -> Credits? {
        // Local models — no credits needed
        return nil
    }

    // MARK: - Helpers

    private func buildRequestBody(from request: ChatRequest, stream: Bool) -> [String: Any] {
        var messages: [[String: Any]] = []

        // Add system prompt as a system message
        if let systemPrompt = request.systemPrompt {
            messages.append(["role": "system", "content": systemPrompt])
        }

        for msg in request.messages {
            messages.append(["role": msg.role.rawValue, "content": msg.content])
        }

        var body: [String: Any] = [
            "model": request.model,
            "messages": messages,
            "stream": stream
        ]

        var options: [String: Any] = [:]
        if let maxTokens = request.maxTokens { options["num_predict"] = maxTokens }
        if let temperature = request.temperature { options["temperature"] = temperature }
        if !options.isEmpty { body["options"] = options }

        return body
    }

    private func parseOllamaResponse(_ json: [String: Any], model: String) -> ChatResponse {
        let message = json["message"] as? [String: Any]
        let content = message?["content"] as? String ?? ""
        let promptTokens = json["prompt_eval_count"] as? Int ?? 0
        let completionTokens = json["eval_count"] as? Int ?? 0

        return ChatResponse(
            id: UUID().uuidString,
            model: model,
            content: content,
            role: "assistant",
            finishReason: "stop",
            usage: ChatResponse.Usage(
                promptTokens: promptTokens,
                completionTokens: completionTokens,
                totalTokens: promptTokens + completionTokens
            ),
            created: Date()
        )
    }
}