# main.ludic — the self-hosted Ludic front-end.
#
# ludicc lexes, parses, checks and lowers a .ludic file to LLVM IR, then drives
# clang (the IR assembler + system linker, the same role rustc/swiftc give it)
# to produce a native binary. No C is compiled: the emitted IR is Ludic's, and
# clang only assembles and links it.
#
#   ludicc app.ludic -o bin/app            # native binary (windowed if a game)
#   ludicc app.ludic -o bin/app --headless # force headless
#   ludicc app.ludic --emit-llvm -o app.ll # stop at the IR
#   ludic  app.ludic                       # compile to a temp binary and run it
#
# The multi-call twist: when argv[0] is "ludic" it defaults to compile-and-run.
# With no -o and no run, IR still goes to stdout — the contract build.sh and
# reseed.sh rely on, so the bootstrap is untouched.

# basename: the part of a path after the last '/'.
fn base_name(path: ptr) -> ptr {
  var last = 0 - 1
  var i = 0
  while peek8(path, i) != 0 { if peek8(path, i) == 47 { last = i };  i = i + 1 }
  return substr(path, last + 1, i - (last + 1))
}

# drop a trailing ".ludic" if present
fn strip_ludic(name: ptr) -> ptr {
  let n = len(name)
  if n > 6 {
    if (substr(name, n - 6, 6) == ".ludic") { return substr(name, 0, n - 6) }
  }
  return name
}

# env var with a fallback when unset
fn getenv_or(name: ptr, dflt: ptr) -> ptr {
  let v = os_getenv(name)
  if (v == null) { return dflt }
  return v
}

# guarantee a directory string ends in '/' so path_join concatenates cleanly
fn ensure_slash(d: ptr) -> ptr {
  let n = len(d)
  if n == 0 { return d }
  if peek8(d, n - 1) == 47 { return d }
  return (d + ("/"))
}

fn die(msg: ptr) -> void {
  file_write(file_stderr(), msg, len(msg))
  os_exit(1)
}

entry {
  var path = null
  var out  = null
  var want = 0            # 0 = auto, 1 = windowed, 2 = headless
  var emit_ir = false     # --emit-llvm: stop after writing IR
  var fmt = false         # --fmt: lex + parse only, then exit (the doc-check gate)
  var save = false        # --save-temps: keep the intermediate .ll
  var run = false         # compile then execute the result

  # multi-call: invoked as `ludic` -> run mode by default
  if (base_name(os_arg(0)) == "ludic") { run = true }

  var ai = 1
  while ai < os_argc() {
    let a = os_arg(ai)
    if (a == ("--windowed")) { want = 1 }
    else { if (a == ("--headless")) { want = 2 }
    else { if (a == ("--emit-llvm")) { emit_ir = true }
    else { if (a == ("--fmt")) { fmt = true }
    else { if (a == ("--save-temps")) { save = true }
    else { if (a == ("--run")) { run = true }
    else { if (a == ("-o")) { ai = ai + 1;  if ai < os_argc() { out = os_arg(ai) } }
    else {
      # an unknown flag is ignored (with a note) rather than mistaken for the
      # input file — '-' is ASCII 45
      if peek8(a, 0) == 45 {
        let m = `ludicc: ignoring unknown flag {a}\n`
        file_write(file_stderr(), m, len(m))
      } else { path = a }
    } } } } } } }
    ai = ai + 1
  }

  if (path == null) {
    die("usage: ludicc <file.ludic> [-o out] [--windowed|--headless] [--emit-llvm] [--save-temps]\n")
  }
  let src = read_file(path)
  if (src == null) { die("ludicc: cannot open input\n") }

  cur_dir = dir_of(path)
  lex(src)
  parse_program()

  # --fmt is the doc-check gate: reaching here means it lexed and parsed. A parse
  # error would already have exited nonzero, so a clean parse exits 0. (Canonical
  # formatting output is not yet reimplemented on the self-hosted toolchain.)
  if fmt { os_exit(0) }

  maybe_splice_runtime()

  # a game gets a window by default; a plain program stays headless. An explicit
  # flag always wins. The stdout-IR path (no target) also stays headless, which
  # is what reseed.sh compiles the compiler itself with.
  let has_target = run or ((out != null))
  if want == 1 { g_windowed = true }
  else { if want == 2 { g_windowed = false }
  else { g_windowed = has_target and has_systems() } }

  emit_program()

  # --emit-llvm, or no binary target: emit IR and stop (stdout when out is null).
  if emit_ir { ir_flush(out);  return }
  if not has_target { ir_flush(null);  return }

  # a run with no explicit -o lands in a temp file
  if run and (out == null) {
    out = `/tmp/ludic-run-{strip_ludic(base_name(path))}`
  }

  # make the output directory if the user asked for e.g. bin/app
  let odir = dir_of(out)
  if len(odir) > 0 { os_system(`mkdir -p {odir}`) }

  let ll = `{out}.ll`
  if not ir_flush(ll) { die("ludicc: cannot write IR\n") }

  let cc   = getenv_or("LUDIC_CC", "clang")
  let home = ensure_slash(getenv_or("LUDIC_HOME", dir_of(os_arg(0))))

  # clang twice: assemble the IR, then link. A windowed build adds the macOS
  # platform layer and the Cocoa framework.
  # -Wno-override-module: our IR carries an explicit target triple, which clang
  # would otherwise warn about on every build.
  var cmd = `{cc} -O2 -Wno-override-module {ll}`
  if g_windowed {
    let cocoa = path_join(home, "runtime/native/cocoa.ll")
    cmd = `{cmd} {cocoa} -framework Cocoa -Wl,-rpath,@loader_path`
  }
  cmd = `{cmd} -o {out}`

  let rc = os_system(cmd)
  if not save { os_system(`rm -f {ll}`) }
  if rc != 0 { die("ludicc: link failed\n") }

  # run mode: execute the binary we just built and forward its exit code
  if run {
    let st = os_system(out)
    os_exit(((st >> 8) & 255))
  }
}