#!/usr/bin/env python3
"""Generate the LuaLS stub for the firmware's Lua API.

Adapted from crosspoint-reader's scripts/gen_lua_stubs.py. The emitted format is
deliberately identical so an editor configured for one repo works for the other; the
parser differs because this firmware registers bindings as annotated luaL_Reg tables
rather than addFunction() calls, which keeps a module's documentation contiguous.

    python3 scripts/gen_lua_stubs.py            # write the stub
    python3 scripts/gen_lua_stubs.py --check    # exit 1 if it is stale
"""

import re
import sys
from pathlib import Path

ROOT = Path(__file__).resolve().parent.parent
SOURCES = sorted((ROOT / "src/lua/bindings").glob("*.cpp"))
OUTPUT = ROOT / "stubs/esp32lcd.lua"

TYPES = {"int": "integer", "bool": "boolean"}

ENTRY = re.compile(r'^\s*\{"(?P<name>\w+)",\s*\w+\}')
TABLE = re.compile(r"static const luaL_Reg (?P<var>\w+)\[\]")
BIND = re.compile(r'luaL_newlib\(L,\s*(?P<var>\w+)\);\s*\n\s*lua_setglobal\(L,\s*"(?P<global>\w+)"\)')
DOC = re.compile(r"^\s*//\s*---\s?(?P<text>.*)$")
PARAM = re.compile(r"^\s*//\s*@param\s+(?P<name>\w+)\s+(?P<type>\S+)(?:\s+(?P<desc>.*))?$")
RETURN = re.compile(r"^\s*//\s*@return\s+(?P<type>\S+)(?:\s+(?P<desc>.*))?$")
TAG = re.compile(r"^\s*//\s*@(?P<tag>\w+)")


def lua_type(raw):
    """`int|nil` becomes `integer?`, matching how LuaLS spells optionality."""
    optional = raw.endswith("|nil")
    if optional:
        raw = raw[: -len("|nil")]
    mapped = TYPES.get(raw, raw)
    return f"{mapped}?" if optional else mapped


def parse(path):
    """Collect {var: [function, ...]} and {var: global name} from one file."""
    text = path.read_text()
    tables, bindings = {}, {}

    for match in BIND.finditer(text):
        bindings[match.group("var")] = match.group("global")

    lines = text.splitlines()
    var, pending = None, {"doc": [], "params": [], "returns": []}

    def reset():
        return {"doc": [], "params": [], "returns": []}

    for line in lines:
        table = TABLE.search(line)
        if table:
            var = table.group("var")
            tables.setdefault(var, [])
            pending = reset()
            continue
        if var is None:
            continue

        doc = DOC.match(line)
        if doc:
            pending["doc"].append(doc.group("text").strip())
            continue
        param = PARAM.match(line)
        if param:
            pending["params"].append(
                (param.group("name"), lua_type(param.group("type")), (param.group("desc") or "").strip())
            )
            continue
        ret = RETURN.match(line)
        if ret:
            pending["returns"].append((lua_type(ret.group("type")), (ret.group("desc") or "").strip()))
            continue
        tag = TAG.match(line)
        if tag:
            raise SystemExit(f"{path.name}: unknown tag @{tag.group('tag')}")

        entry = ENTRY.match(line)
        if entry:
            name = entry.group("name")
            if not pending["doc"]:
                raise SystemExit(f"{path.name}: {name} is registered without a description")
            tables[var].append((name, pending))
            pending = reset()
            continue
        if "};" in line:
            var = None

    return tables, bindings


def render(modules):
    out = [
        "---@meta",
        "",
        "-- Generated by scripts/gen_lua_stubs.py. Do not edit.",
        "-- Point your editor's Lua language server at this file to get completion for the",
        "-- firmware API inside sdcard/apps and sdcard/lib.",
        "",
    ]
    for global_name in sorted(modules):
        functions = modules[global_name]
        out.append(f"---@class {global_name}lib")
        out.append(f"{global_name} = {{}}")
        out.append("")
        for name, meta in functions:
            for line in meta["doc"]:
                out.append(f"--- {line}" if line else "---")
            for param, type_, desc in meta["params"]:
                out.append(f"---@param {param} {type_}{(' ' + desc) if desc else ''}")
            for type_, desc in meta["returns"]:
                out.append(f"---@return {type_}{(' ' + desc) if desc else ''}")
            args = ", ".join(param for param, _, _ in meta["params"])
            out.append(f"function {global_name}.{name}({args}) end")
            out.append("")
    out.extend(
        [
            "-- Callbacks an app may define as globals:",
            "--   init()                   once, before the first draw (required)",
            "--   draw()                   every 33 ms while the app runs",
            "--   on_tick()                at the interval app.setTickInterval() asked for",
            "--   on_touch_down(x, y)      finger down",
            "--   on_touch_up(x, y)        finger up",
            "--   on_touch(x, y)           tap, fired on release like a click",
            "",
        ]
    )
    return "\n".join(out)


def main():
    modules = {}
    for path in SOURCES:
        tables, bindings = parse(path)
        for var, functions in tables.items():
            if var not in bindings:
                continue  # a table that is never installed as a global documents nothing
            modules.setdefault(bindings[var], []).extend(functions)

    if not modules:
        raise SystemExit("no annotated bindings found")

    rendered = render(modules)
    if "--check" in sys.argv:
        current = OUTPUT.read_text() if OUTPUT.exists() else ""
        if current != rendered:
            raise SystemExit(f"{OUTPUT.relative_to(ROOT)} is stale; run scripts/gen_lua_stubs.py")
        return
    OUTPUT.parent.mkdir(parents=True, exist_ok=True)
    OUTPUT.write_text(rendered)
    print(f"wrote {OUTPUT.relative_to(ROOT)}: {sum(len(f) for f in modules.values())} functions")


if __name__ == "__main__":
    main()