#!/usr/bin/env python3
"""Turns proto/cmdids.txt into a constant header plus a name table for logging."""
import argparse
import os


def write_if_changed(path, text):
    if os.path.exists(path):
        with open(path, encoding="utf-8") as fh:
            if fh.read() == text:
                return
    with open(path, "w", encoding="utf-8", newline="\n") as fh:
        fh.write(text)


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--input", required=True)
    ap.add_argument("--out-dir", required=True)
    args = ap.parse_args()

    entries = []
    with open(args.input, encoding="utf-8") as fh:
        for line in fh:
            line = line.split("#", 1)[0].strip()
            if not line or "=" not in line:
                continue
            name, value = (part.strip() for part in line.split("=", 1))
            if name == "None":
                continue
            entries.append((name, int(value)))

    entries.sort(key=lambda e: e[0])

    h = ["// generated by tools/gen_cmdids.py -- do not edit", "#pragma once", "#include <cstdint>",
         "#include <string>", "", "namespace cmd {", ""]
    for name, value in entries:
        h.append(f"constexpr uint16_t {name} = {value};")
    h += ["", "// packet name for logging; \"Unknown(<id>)\" when the dump has no name for it",
          "std::string name(uint16_t id);", "",
          "// 0 when the dump has no packet by that name",
          "uint16_t id(const std::string& name);", "", "}  // namespace cmd", ""]
    write_if_changed(os.path.join(args.out_dir, "cmd_ids.h"), "\n".join(h))

    # first name wins for aliased ids, so the table stays 1:1
    by_id = {}
    for name, value in entries:
        by_id.setdefault(value, name)

    c = ["// generated by tools/gen_cmdids.py -- do not edit", '#include "net/cmd_ids.h"', "",
         "#include <unordered_map>", "", "namespace cmd {", "namespace {",
         "const std::unordered_map<uint16_t, const char*>& table() {",
         "    static const std::unordered_map<uint16_t, const char*> t = {"]
    for value, name in sorted(by_id.items()):
        c.append(f'        {{{value}, "{name}"}},')
    c += ["    };", "    return t;", "}", "",
          "const std::unordered_map<std::string, uint16_t>& reverse() {",
          "    static const std::unordered_map<std::string, uint16_t> t = [] {",
          "        std::unordered_map<std::string, uint16_t> m;",
          "        for (const auto& [k, v] : table()) m.emplace(v, k);",
          "        return m;", "    }();", "    return t;", "}",
          "}  // namespace", "",
          "std::string name(uint16_t id) {", "    auto it = table().find(id);",
          "    if (it != table().end()) return it->second;",
          '    return "Unknown(" + std::to_string(id) + ")";', "}", "",
          "uint16_t id(const std::string& n) {", "    auto it = reverse().find(n);",
          "    return it == reverse().end() ? 0 : it->second;", "}", "",
          "}  // namespace cmd", ""]
    write_if_changed(os.path.join(args.out_dir, "cmd_ids.cpp"), "\n".join(c))
    print(f"  {len(entries)} cmd ids, {len(by_id)} unique")


if __name__ == "__main__":
    main()