import AppKit
import Foundation

/// Headless conversion, used for verification and scripting:
///
///     Konverter --convert a.png b.pdf --to jpg
///     Konverter --convert clip.mov --tool trimVideo --param start=0:02 --param end=0:05
enum CLI {
    static func run() -> Int32 {
        let arguments = Array(CommandLine.arguments.dropFirst())

        guard let convertIndex = arguments.firstIndex(of: "--convert") else {
            FileHandle.standardError.write(Data("usage: Konverter --convert <files…> --to <ext>\n".utf8))
            return 2
        }

        var files: [URL] = []
        var target: Format?
        var tool: ToolID?
        var params = ToolParams()

        var index = convertIndex + 1
        while index < arguments.count {
            let argument = arguments[index]
            switch argument {
            case "--to":
                index += 1
                if index < arguments.count { target = Format(rawValue: arguments[index]) }
            case "--tool":
                index += 1
                if index < arguments.count { tool = ToolID(rawValue: arguments[index]) }
            case "--param":
                index += 1
                if index < arguments.count {
                    let pair = arguments[index].split(separator: "=", maxSplits: 1).map(String.init)
                    if pair.count == 2 { params[pair[0]] = pair[1] }
                }
            default:
                if !argument.hasPrefix("--") {
                    files.append(URL(fileURLWithPath: argument))
                }
            }
            index += 1
        }

        guard !files.isEmpty else {
            FileHandle.standardError.write(Data("no input files\n".utf8))
            return 2
        }

        do {
            if let tool {
                let outcome = try ToolRunner.run(tool: tool, inputs: files, params: params)
                if let message = outcome.message {
                    print(message)
                }
                for output in outcome.outputs { print(output.path) }
                return outcome.outputs.isEmpty && outcome.message == nil ? 1 : 0
            }

            guard let target else {
                FileHandle.standardError.write(Data("--to is required\n".utf8))
                return 2
            }

            var written: [URL] = []
            for file in files {
                let destination = OutputNaming.destination(for: file, format: target)
                let outputs = try Converter.convert(source: file, to: target, at: destination)
                written.append(contentsOf: outputs)
            }
            for output in written { print(output.path) }
            return written.isEmpty ? 1 : 0
        } catch {
            let message = (error as? LocalizedError)?.errorDescription ?? error.localizedDescription
            FileHandle.standardError.write(Data((message + "\n").utf8))
            return 1
        }
    }
}