/**
 * 第 10 章 · 实战项目 — CLI 入口
 *
 * 用法：
 *   todo add "学 Kotlin"
 *   todo add "做项目" --priority HIGH --due 2026-05-01
 *   todo list [active|done|all]
 *   todo done <id>
 *   todo rm <id>
 *   todo stats
 *   todo help
 */

import kotlinx.coroutines.runBlocking

fun main(args: Array<String>) = runBlocking {
    try {
        val cmd = CommandParser.parse(args)
        execute(cmd)
    } catch (e: IllegalArgumentException) {
        System.err.println("❌ ${e.message}")
        kotlin.system.exitProcess(1)
    } catch (e: IllegalStateException) {
        System.err.println("❌ ${e.message}")
        kotlin.system.exitProcess(1)
    } catch (e: Throwable) {
        System.err.println("❌ 内部错误: ${e.message}")
        e.printStackTrace()
        kotlin.system.exitProcess(2)
    }
}

private suspend fun execute(cmd: Command) {
    val todos = Repository.load()

    when (cmd) {
        is Command.Add -> {
            val newTodo = Todo(
                id = Repository.nextId(todos),
                title = cmd.title,
                priority = cmd.priority,
                due = cmd.due,
            )
            todos.add(newTodo)
            Repository.save(todos)
            println("✅ 添加成功: ${newTodo.format()}")
        }

        is Command.Done -> {
            val idx = todos.indexOfFirst { it.id == cmd.id }
            require(idx >= 0) { "找不到 #${cmd.id}" }
            todos[idx] = todos[idx].copy(done = true)
            Repository.save(todos)
            println("✅ 完成: ${todos[idx].format()}")
        }

        is Command.Remove -> {
            val removed = todos.removeIf { it.id == cmd.id }
            require(removed) { "找不到 #${cmd.id}" }
            Repository.save(todos)
            println("🗑️  删除 #${cmd.id}")
        }

        is Command.List -> {
            val filtered = todos.filter {
                when (cmd.filter) {
                    Command.Filter.ACTIVE -> !it.done
                    Command.Filter.DONE -> it.done
                    Command.Filter.ALL -> true
                }
            }
            // 按优先级倒序 + 创建时间正序
            val sorted = filtered.sortedWith(
                compareByDescending<Todo> { it.priority.ordinal }
                    .thenBy { it.createdAt }
            )
            if (sorted.isEmpty()) {
                println("(空)")
            } else {
                sorted.forEach { println(it.format()) }
                println("\n${sorted.summary()}")
            }
        }

        Command.Stats -> {
            println(todos.summary())
            // 按优先级分组统计
            val byPriority = todos.groupingBy { it.priority }.eachCount()
            println("按优先级:")
            Priority.entries.forEach { p ->
                println("  ${p.name.padEnd(4)}: ${byPriority[p] ?: 0}")
            }
        }

        Command.Help -> println(HELP_TEXT)
    }
}

private val HELP_TEXT = """
    Todo CLI - 一个用 Kotlin 写的 todo 工具
    
    用法:
      todo add <title> [--priority LOW|MID|HIGH] [--due YYYY-MM-DD]
      todo done <id>          标记完成
      todo rm <id>            删除
      todo list [active|done|all]
      todo stats              统计
      todo help               显示帮助
    
    例子:
      todo add "学 Kotlin"
      todo add "做项目" --priority HIGH --due 2026-05-01
      todo list active
""".trimIndent()