cli.kt/src/commonMain/kotlin/com/infendro/cli/command/Command.kt

package com.infendro.cli.command

import com.infendro.cli.command.Execution
import com.infendro.cli.argument.Argument
import com.infendro.cli.exception.build.*
import com.infendro.cli.exception.run.ArgumentCountException
import com.infendro.cli.exception.run.InvalidArgumentException
import com.infendro.cli.exception.run.UnknownArgumentException
import com.infendro.cli.exception.run.UnknownCommandException
import com.infendro.cli.util.Regex.ARGUMENT
import com.infendro.cli.util.Regex.ARGUMENT_NAME
import com.infendro.cli.util.Regex.COMMAND_NAME

class Command private constructor(
    private val index: Int,
    private val name: String?,
    private val commands: List<Command>,
    private val arguments: List<Argument<*>>,
    private val block: Execution.() -> Unit,
) {
    private val nextIndex: Int
        get() = index + 1

    fun run(
        args: Array<String>,
    ) {
        val index = args
            .withIndex()
            .find { (_, value) -> value.startsWith("--") }
            ?.index ?: args.size

        val cmd = args.slice(0..<index)
        val arg = args.slice(index..<args.size)

        try {
            run(cmd, arg)
        } catch (e: UnknownCommandException) {
            println("""unknown command "${e.command}"""")
        } catch (e: InvalidArgumentException) {
            println("""invalid argument "${e.argument}"""")
        } catch (e: UnknownArgumentException) {
            println("""unknown argument "${e.argument}"""")
        } catch (e: ArgumentCountException) {
            when {
                e.min == e.max -> println("""argument "${e.argument}" must appear ${e.min} times""")
                e.max == Int.MAX_VALUE -> println("""argument "${e.argument}" must appear at least ${e.min} times""")
                else -> println("""argument "${e.argument}" must appear between ${e.min} and ${e.max} times""")
            }
        }
    }

    private fun run(
        cmd: List<String>,
        arg: List<String>,
    ) {
        if (index == cmd.lastIndex) {
            Execution(
                parseCmd(cmd),
                parseArg(arg),
            ).block()
        } else {
            val command = commands.firstOrNull() { it.name == cmd[nextIndex] || it.name == null }
                ?: throw UnknownCommandException(cmd[nextIndex])
            command.run(cmd, arg)
        }
    }

    private fun parseCmd(
        cmd: List<String>,
    ): List<Execution.Cmd> {
        return cmd.map { Execution.Cmd(it) }
    }

    private fun parseArg(
        arg: List<String>,
    ): List<Execution.Arg> {
        val result = mutableListOf<Execution.Arg>()

        for (argument in arg) {
            val match = ARGUMENT.matchEntire(argument)
                ?: throw InvalidArgumentException(argument)

            val name = match.groups["name"]!!.value
            val value = match.groups["value"]?.value

            if (arguments.none { it.name == name })
                throw UnknownArgumentException(name)

            result += Execution.Arg(name, value)
        }

        arguments
            .forEach { argument ->
                val count = result.count { it.name == argument.name }
                if (count !in argument.min..argument.max)
                    throw ArgumentCountException(argument.name, argument.min, argument.max)
            }

        return result
    }

    class Builder internal constructor(
        private val index: Int,
        private val name: String?,
    ) {
        private val commands = mutableListOf<Command>()
        private val arguments = mutableListOf<Argument<*>>()
        private lateinit var block: Execution.() -> Unit

        private val nextIndex: Int
            get() = index + 1

        fun command(
            name: String? = null,
            block: Builder.(Key) -> Unit,
        ) {
            if (name != null && !COMMAND_NAME.matches(name))
                throw IllegalCommandNameException(name)

            if (commands.any { it.name == name })
                throw DuplicateCommandException(name)

            val builder = Builder(nextIndex, name)
            builder.block(Key(nextIndex))
            val command = builder.build()

            commands.add(command)
        }

        fun argument(
            argument: Argument<*>,
        ) {
            if (!ARGUMENT_NAME.matches(argument.name))
                throw IllegalArgumentNameException(argument.name)

            if (arguments.any { it.name == argument.name })
                throw DuplicateArgumentException(argument.name)

            arguments.add(argument)
        }

        fun arguments(
            vararg arguments: Argument<*>,
        ) {
            for (argument in arguments) {
                argument(argument)
            }
        }

        fun execute(
            block: Execution.() -> Unit,
        ) {
            if (this::block.isInitialized)
                throw DuplicateExecuteException()

            this.block = block
        }

        fun build(): Command {
            if (!this::block.isInitialized)
                throw NoExecuteException()

            return Command(index, name, commands, arguments, block)
        }
    }

    class Key(
        internal val index: Int,
    )
}

fun cli(
    block: Command.Builder.() -> Unit,
): Command {
    val builder = Command.Builder(-1, null)
    builder.block()
    return builder.build()
}