import Foundation

// MARK: - Claude Code CLI as the chat brain
//
// Every message runs the user's own `claude` binary headless:
//   claude -p <text> --output-format stream-json --verbose --include-partial-messages
//          [--resume <session id>] [--model <alias>]
// in the chat folder (Settings → Chat), on the user's Claude subscription — no API key.
// The session id from the first reply is kept, so the next message continues the same
// conversation; "New conversation" forgets it. MCP servers, skills, CLAUDE.md and memory
// all come along because it is the real CLI. Tool permissions go through the usual
// Claude Code hooks, so they show up as Allow / Deny cards in the notch.

enum ClaudeCodeCLIError: LocalizedError {
    case notFound
    case failed(String)

    var errorDescription: String? {
        switch self {
        case .notFound:
            "Claude Code CLI не найден. Установите его или укажите путь в Настройки → Чат."
        case .failed(let message):
            message
        }
    }
}

@MainActor
final class ClaudeCodeCLI {
    static let shared = ClaudeCodeCLI()

    /// Models offered in the picker. Empty id = whatever the CLI is configured to use.
    static let models: [(id: String, label: String)] = [
        ("", "По умолчанию"),
        ("opus", "Opus"),
        ("sonnet", "Sonnet"),
        ("haiku", "Haiku"),
    ]

    private(set) var sessionID: String?
    private var process: Process?

    var isRunning: Bool { process?.isRunning == true }

    func newConversation() {
        cancel()
        sessionID = nil
    }

    func cancel() {
        if let p = process, p.isRunning { p.terminate() }
        process = nil
    }

    // MARK: Locating the binary

    /// The `claude` binary: the path from Settings when set, else the usual install spots.
    /// GUI apps don't get the shell's PATH, so we look ourselves.
    nonisolated static func resolveBinary(custom: String) -> String? {
        let fm = FileManager.default
        let trimmed = (custom as NSString).expandingTildeInPath
            .trimmingCharacters(in: .whitespacesAndNewlines)
        if !trimmed.isEmpty { return fm.isExecutableFile(atPath: trimmed) ? trimmed : nil }
        let home = fm.homeDirectoryForCurrentUser.path
        let candidates = [
            "\(home)/.local/bin/claude",
            "\(home)/.claude/local/claude",
            "/opt/homebrew/bin/claude",
            "/usr/local/bin/claude",
            "\(home)/.npm-global/bin/claude",
        ]
        return candidates.first { fm.isExecutableFile(atPath: $0) }
    }

    /// The child's environment: ours, minus the markers that make `claude` refuse to start
    /// inside another Claude Code session, plus the common bin folders on PATH so MCP
    /// servers (node, uvx, python…) resolve like they do in a terminal.
    nonisolated static func childEnvironment() -> [String: String] {
        var env = ProcessInfo.processInfo.environment
        env.removeValue(forKey: "CLAUDECODE")
        env.removeValue(forKey: "CLAUDE_CODE_ENTRYPOINT")
        let home = FileManager.default.homeDirectoryForCurrentUser.path
        let extra = ["\(home)/.local/bin", "/opt/homebrew/bin", "/opt/homebrew/sbin",
                     "/usr/local/bin", "/usr/bin", "/bin", "/usr/sbin", "/sbin"]
        var parts = (env["PATH"] ?? "").split(separator: ":").map(String.init)
        for dir in extra where !parts.contains(dir) { parts.append(dir) }
        env["PATH"] = parts.joined(separator: ":")
        return env
    }

    // MARK: Running a turn

    /// Sends `prompt` and streams the visible reply through `onUpdate` (the full text so far).
    /// Returns the final text. Throws on a missing binary, a crash or a CLI-reported error.
    func send(prompt: String,
              model: String,
              workingDirectory: String,
              binaryPath: String,
              permissionMode: String,
              onUpdate: @escaping @MainActor (String) -> Void) async throws -> String {
        cancel()
        guard let binary = Self.resolveBinary(custom: binaryPath) else { throw ClaudeCodeCLIError.notFound }

        var args = ["-p", prompt,
                    "--output-format", "stream-json",
                    "--verbose",
                    "--include-partial-messages",
                    "--append-system-prompt", Self.notchPrompt]
        if let sessionID { args += ["--resume", sessionID] }
        if !model.isEmpty { args += ["--model", model] }
        // Never bypass: the chat gets untrusted input (dropped files, window titles, URLs).
        let allowedModes: Set<String> = ["acceptEdits", "plan"]
        if allowedModes.contains(permissionMode) { args += ["--permission-mode", permissionMode] }

        let p = Process()
        p.executableURL = URL(fileURLWithPath: binary)
        p.arguments = args
        p.environment = Self.childEnvironment()
        let dir = (workingDirectory as NSString).expandingTildeInPath
        var isDir: ObjCBool = false
        p.currentDirectoryURL = FileManager.default.fileExists(atPath: dir, isDirectory: &isDir) && isDir.boolValue
            ? URL(fileURLWithPath: dir)
            : FileManager.default.homeDirectoryForCurrentUser
        p.standardInput = FileHandle.nullDevice
        let out = Pipe(), err = Pipe()
        p.standardOutput = out
        p.standardError = err
        process = p

        let stream = AsyncStream<String> { continuation in
            let handle = out.fileHandleForReading
            Task.detached {
                do {
                    for try await line in handle.bytes.lines { continuation.yield(line) }
                } catch {}
                continuation.finish()
            }
        }

        try p.run()

        var parser = StreamParser()
        for await line in stream {
            if let update = parser.consume(line) {
                if let id = update.sessionID { sessionID = id }
                if update.textChanged { onUpdate(parser.visibleText) }
            }
        }
        p.waitUntilExit()
        if process === p { process = nil }

        if let error = parser.errorMessage {
            if error.localizedCaseInsensitiveContains("authenticate") || error.localizedCaseInsensitiveContains("login") {
                AgentAuth.shared.reportAuthError(.claude)
                throw ClaudeCodeCLIError.failed("Claude Code не авторизован. Выполните `claude /login` в терминале.")
            }
            // A resume that points at a gone session: start fresh next time.
            if error.localizedCaseInsensitiveContains("No conversation found") { sessionID = nil }
            throw ClaudeCodeCLIError.failed(error)
        }
        if p.terminationReason == .uncaughtSignal { throw CancellationError() }
        if parser.finalText == nil, p.terminationStatus != 0 {
            let stderr = String(data: err.fileHandleForReading.readDataToEndOfFile(), encoding: .utf8) ?? ""
            let last = stderr.split(separator: "\n").last.map(String.init) ?? "код выхода \(p.terminationStatus)"
            throw ClaudeCodeCLIError.failed("claude: \(last)")
        }
        return parser.finalText ?? parser.visibleText
    }

    private static let notchPrompt = """
    You are talking through BroV, a tiny assistant living in the notch of the user's Mac. \
    The chat window is small: keep answers compact, use light Markdown (short paragraphs, lists, \
    **bold**, `code`), avoid tables and big headings. Respond in the user's language.
    """
}

// MARK: - stream-json parsing

/// Turns the CLI's stream-json lines into the text shown in the chat bubble:
/// assistant text as it streams, plus a short `⚙ Tool` line for each tool call.
struct StreamParser {
    struct Update {
        var sessionID: String?
        var textChanged = false
    }

    private(set) var visibleText = ""
    private(set) var finalText: String?
    private(set) var errorMessage: String?
    /// Text of the message currently streaming (partial deltas), not yet committed.
    private var liveText = ""
    private var committed = ""

    mutating func consume(_ line: String) -> Update? {
        guard let data = line.data(using: .utf8),
              let json = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
              let type = json["type"] as? String else { return nil }
        var update = Update(sessionID: json["session_id"] as? String)

        switch type {
        case "stream_event":
            guard let event = json["event"] as? [String: Any] else { break }
            if event["type"] as? String == "content_block_delta",
               let delta = event["delta"] as? [String: Any],
               delta["type"] as? String == "text_delta",
               let text = delta["text"] as? String {
                liveText += text
                update.textChanged = refresh()
            } else if event["type"] as? String == "message_start" {
                liveText = ""
            }

        case "assistant":
            // The complete message: commit its text (replacing the partial deltas) and tools.
            guard let message = json["message"] as? [String: Any],
                  let content = message["content"] as? [[String: Any]] else { break }
            if json["error"] != nil || message["model"] as? String == "<synthetic>" {
                if let text = content.first(where: { $0["type"] as? String == "text" })?["text"] as? String {
                    errorMessage = text
                }
                break
            }
            var piece = ""
            for block in content {
                switch block["type"] as? String {
                case "text":
                    if let t = block["text"] as? String { piece += t }
                case "tool_use":
                    let name = block["name"] as? String ?? "tool"
                    piece += (piece.isEmpty ? "" : "\n\n") + "`⚙ \(Self.toolLabel(name, block["input"]))`"
                default: break
                }
            }
            if !piece.isEmpty {
                committed += (committed.isEmpty ? "" : "\n\n") + piece.trimmingCharacters(in: .whitespacesAndNewlines)
            }
            liveText = ""
            update.textChanged = refresh()

        case "result":
            let isError = json["is_error"] as? Bool ?? false
            let result = json["result"] as? String
            if isError {
                if errorMessage == nil { errorMessage = result ?? "Claude Code вернул ошибку." }
            } else {
                // Keep the tool trail when there was one; otherwise the clean final answer.
                finalText = committed.isEmpty ? (result ?? "") : committed
            }

        default:
            break
        }
        return update
    }

    private mutating func refresh() -> Bool {
        let live = liveText.trimmingCharacters(in: .whitespacesAndNewlines)
        let next = live.isEmpty ? committed : committed + (committed.isEmpty ? "" : "\n\n") + live
        guard next != visibleText else { return false }
        visibleText = next
        return true
    }

    /// "Bash: git status", "Read: Foo.swift", or just the tool name.
    static func toolLabel(_ name: String, _ input: Any?) -> String {
        guard let input = input as? [String: Any] else { return name }
        let detail: String?
        if let command = input["command"] as? String {
            detail = command
        } else if let path = (input["file_path"] ?? input["path"] ?? input["notebook_path"]) as? String {
            detail = (path as NSString).lastPathComponent
        } else if let pattern = input["pattern"] as? String {
            detail = pattern
        } else if let url = input["url"] as? String {
            detail = url
        } else if let query = input["query"] as? String {
            detail = query
        } else {
            detail = nil
        }
        guard var d = detail?.replacingOccurrences(of: "\n", with: " "), !d.isEmpty else { return name }
        if d.count > 60 { d = String(d.prefix(57)) + "…" }
        d = d.replacingOccurrences(of: "`", with: "'")
        return "\(name): \(d)"
    }
}