# 这就是一个完整的 Nim 程序
echo "Hello, Nim!"

nim c -r hello.nim

# 编译时优化：常量折叠
const
  Size = 1024 * 1024  # 编译期计算，零运行时开销

# 零成本抽象
proc sumPositive(data: seq[int]): int =
  result = 0
  for x in data:
    if x > 0:
      result += x

# 列表推导风格
import std/sequtils

let
  numbers = @[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
  evens = numbers.filterIt(it mod 2 == 0)
  squares = evens.mapIt(it * it)

echo squares  # @[4, 16, 36, 64, 100]

# 模式匹配风格的 case 语句
proc describe(x: int): string =
  case x
  of 0: "零"
  of 1..9: "个位数"
  of 10..99: "两位数"
  else: "更大的数"

echo describe(42)  # "两位数"

# 用模板(template)创造新语法
template `??`(a, b: untyped): untyped =
  if a != nil: a else: b

let name: string = nil ?? "default"
echo name  # "default"

nim c -o:myapp main.nim

nim c --genScript main.nim
# 查看生成的 main.c

# frontend.nim
proc greet(name: cstring) {.importjs: "console.log('Hello, ' + #)".}

greet("Nim")

nim js -o:frontend.js frontend.nim
# 生成的 frontend.js 可以直接在浏览器中使用

when defined(js):
  proc alert(msg: string) {.importjs: "alert(#)".}
  alert("Running in browser!")
elif defined(c):
  echo "Running as native app!"

# mytool.nim - 一个简单的文件搜索工具
import std/[os, strutils, parseopt]

proc searchFile(path: string, keyword: string) =
  for line in lines(path):
    if keyword in line:
      echo path, ": ", line

proc main() =
  var
    keyword = ""
    dir = "."
  
  for kind, key, val in getopt():
    case kind
    of cmdArgument: keyword = key
    of cmdLongOption, cmdShortOption:
      if key == "dir": dir = val
    of cmdEnd: discard
  
  for path in walkDirRec(dir):
    if path.endsWith(".txt"):
      searchFile(path, keyword)

main()

# server.nim - HTTP API 服务
import jester

routes:
  get "/api/hello":
    resp %*{"message": "Hello, World!"}
  
  get "/api/user/@id":
    resp %*{"id": @"id", "name": "User " & @"id}

# 直接调用系统 API
proc gethostname(name: cstring, len: csize_t): cint {.importc, header: "<unistd.h>".}

var hostname = newString(256)
discard gethostname(hostname, 256)
echo "Hostname: ", hostname

import std/[math, sequtils, algorithm]

# 生成数据并计算统计量
let data = (0..999).mapIt(sin(it.float * 0.01) + rand(1.0))
let sorted = data.sorted()
let median = sorted[sorted.len div 2]
let mean = data.sum() / data.len.float
echo &"Mean: {mean:.4f}, Median: {median:.4f}"

# 基本编译
nim c main.nim                    # 编译（默认 -d:release 未启用）
nim c -r main.nim                 # 编译并运行
nim c -d:release main.nim         # 发布模式（开启优化）
nim c -d:danger main.nim          # 危险模式（关闭所有检查）

# 调试相关
nim c --linedir:on main.nim       # 包含行号信息
nim c --debuginfo main.nim        # 调试信息

# 输出控制
nim c -o:myapp main.nim           # 指定输出文件名
nim c --os:linux --cpu:amd64 main.nim  # 交叉编译

# 代码分析
nim check main.nim                # 仅检查语法
nim doc main.nim                  # 生成文档