# emit_decl.ludic — functions, main, and the whole-program driver. A function's
# body is built into a scratch buffer so entry-block allocas can be spliced in
# ahead of it (see emit_alloca). Returns go through a %retval slot + `ret` label.

function emit_params_sig(d: Node) -> void {
  var i = 0
  while i < len(d.kids) {
    if i > 0 { emit(", ") }
    emit(llty(d.kids[i].ty));  emit(" %arg_");  emit(d.kids[i].s)
    i = i + 1
  }
}

function emit_fn(d: Node) -> void {
  ll_t = 0;  ll_lbl = 0;  g_term = false;  loc_reset();  nloop = 0
  ret_ty = d.ty
  let fbody = buf_new()
  falloc = buf_new()
  let saved = code
  code = fbody
  let rl = llty(ret_ty)
  if not (rl == "void") { buf_puts(falloc, "  %retval = alloca ");  buf_puts(falloc, rl);  buf_puts(falloc, "\n") }
  # params: store each incoming argument into a stack slot
  var i = 0
  while i < len(d.kids) {
    let p = d.kids[i]
    let slot = emit_alloca(llty(p.ty))
    emit("  store ");  emit(llty(p.ty));  emit(" %arg_");  emit(p.s);  emit(", ptr ");  emit(slot);  emit("\n")
    loc_push(p.s, slot, p.ty)
    i = i + 1
  }
  emit_block(d.a)
  if not g_term { emit("  br label %ret\n") }
  emit("ret:\n")
  if (rl == "void") { emit("  ret void\n") }
  else { let r = emit_bind(`load {rl}, ptr %retval`);  emit("  ret ");  emit(rl);  emit(" ");  emit(r);  emit("\n") }
  code = saved
  emit("define ");  emit(rl);  emit(" @fn_");  emit(d.s);  emit("(");  emit_params_sig(d);  emit(") {\nentry:\n")
  emit(buf_str(falloc))
  emit(buf_str(fbody))
  emit("}\n\n")
}

function emit_main(d: Node) -> void {
  ll_t = 0;  ll_lbl = 0;  g_term = false;  loc_reset();  nloop = 0
  ret_ty = "int"
  let fbody = buf_new()
  falloc = buf_new()
  let saved = code
  code = fbody
  buf_puts(falloc, "  %retval = alloca i32\n")
  emit("  store i32 %argc, ptr @L_argc\n")
  emit("  store ptr %argv, ptr @L_argv\n")
  emit("  store i32 0, ptr %retval\n")
  emit_block(d.a)
  if not g_term { emit("  br label %ret\n") }
  emit("ret:\n")
  let r = emit_bind("load i32, ptr %retval")
  emit("  ret i32 ");  emit(r);  emit("\n")
  code = saved
  emit("define i32 @main(i32 %argc, ptr %argv) {\nentry:\n")
  emit(buf_str(falloc))
  emit(buf_str(fbody))
  emit("}\n")
}

function emit_program() -> void {
  head = buf_new()
  code = buf_new()
  g_uses_str = false
  g_uses_intstr = false
  g_uses_strslice = false
  g_uses_loopback = false
  loc_name = new []pointer;  loc_reg = new []pointer;  loc_ty = new []pointer;  loc_mut = new []int
  brk_lbl = new []pointer;   cnt_lbl = new []pointer
  self_stk = new []pointer
  mach_stk = new []Node
  emit_header()
  emit_extern_decls()
  if has_ecs() { emit_ecs_storage() }
  var i = 0
  while i < len(prog) { if prog[i].kind == N_FN { emit_fn(prog[i]) };  i = i + 1 }
  if len(g_events) > 0 { emit_event_fns() }       # EV0: @ev_<E> event-dispatch functions
  if has_ecs() and (len(g_events) > 0 or g_uses_query) { emit_world_table() }   # EV2: the mod reflection ABI (also powers Query.*)
  if has_ecs() { emit_ecs_allocator();  emit_snapshot() }
  if has_ecs() { emit_net() }                     # N2/N3: @Sync serializers + @Owned storage (gated internally)
  if has_ui() { emit_ui_build() }
  if has_systems() and has_entry() {              # N5: game owns its loop via `entry`
    emit_game_defs()                              # system fns, hooks, tick helpers
    i = 0
    while i < len(prog) { if prog[i].kind == N_MAIN { emit_main(prog[i]) };  i = i + 1 }
  }
  else { if has_systems() { emit_game_main() }    # the auto frame loop
  else {
    i = 0
    while i < len(prog) { if prog[i].kind == N_MAIN { emit_main(prog[i]) };  i = i + 1 }
  } }
  if g_uses_loopback { emit_loopback() }         # built-in transport, after all net_send/net_poll uses are seen
  if g_uses_str { emit_str_prelude() }          # @fn_str_eq / @fn_str_concat, after all uses are seen
  if g_uses_intstr { emit_int_str() }           # @fn_int_str, for string(int) in interpolation
  if g_uses_longstr { emit_long_str() }         # @fn_long_str, for string(long) / long interpolation
  if g_uses_strslice { emit_str_slice() }       # @fn_str_slice, for s[a..b]
  if g_uses_mathrt { emit_math_prelude() }       # @fn_fx_sqrt / @fn_fx_sin + the sine table
  if g_uses_textrt { emit_text_prelude() }       # @fn_str_upper/lower/trim/repeat/pad builders
  if g_uses_textrt2 { emit_text2_prelude() }     # @fn_str_replace/join/split builders
  if g_uses_hashrt { emit_hash_prelude() }       # @fn_hash_fnv1a / @fn_hash_crc32 byte hashers
  if g_uses_cryptort { emit_crypto_prelude() }   # @fn_sha256_hex / @fn_hmac_sha256_hex + constant-time compare + CSPRNG
  if g_uses_uuidrt { emit_uuid_prelude() }       # @fn_uuid_v4 / @fn_uuid_v7 / parse / equals (over the crypto CSPRNG)
  if g_uses_noisert { emit_noise_prelude() }     # @fn_noise_value2/perlin2/simplex2/fbm2/cellular2 (Q16.16)
  if g_uses_logrt { emit_log_prelude() }         # @L_log_level + @fn_log_emit (levelled stderr sink)
  if g_uses_osrt { emit_os_prelude() }           # @fn_os_args/platform/arch/save_dir/... (libc env + uname)
  if g_uses_unicodert { emit_unicode_prelude() } # @fn_uni_len/valid/decode/case/truncate/grapheme (UTF-8)
  if g_uses_fsrt { emit_fs_prelude() }           # @fn_fs_*/fn_path_*/fn_mime_* (libc + string ops)
  if g_uses_datert { emit_datetime_prelude() }   # @fn_days_from_civil / @fn_civil_from_days conversions
}

# Flush the emitted IR. With a null path it goes to stdout (the pipe the shell
# drivers read); with a path it is written to that file so ludicc can hand it to
# clang itself.
function ir_flush(path: pointer) -> bool {
  let h = buf_str(head)
  let c = buf_str(code)
  if (path == null) {                             # raw IR to stdout (no trailing newline)
    let out = file_stdout()
    file_write(out, h, len(h))
    file_write(out, c, len(c))
    return true
  }
  let f = file_open(path, "wb")
  if (f == null) { return false }
  file_write(f, h, len(h))
  file_write(f, c, len(c))
  file_close(f)
  return true
}