#!/usr/bin/env python3
"""Generate src/ESP32React/tz_zones.h from interface/src/app/settings/TZ.tsx.

Run from the repo root:
  python3 scripts/generate_tz_zones.py
"""

from __future__ import annotations

import re
import sys
from pathlib import Path

ROOT = Path(__file__).resolve().parents[1]
TZ_TSX = ROOT / "interface" / "src" / "app" / "settings" / "TZ.tsx"
OUT_H = ROOT / "src" / "ESP32React" / "tz_zones.h"


def parse_time_zones(text: str) -> list[tuple[str, str]]:
    match = re.search(
        r"export const TIME_ZONES: Record<string, string> = \{([\s\S]*?)\n\};",
        text,
    )
    if not match:
        raise SystemExit("TIME_ZONES table not found in TZ.tsx")
    entries = re.findall(r"'((?:\\'|[^'])*)': '((?:\\'|[^'])*)'", match.group(1))
    if not entries:
        raise SystemExit("no TIME_ZONES entries parsed")
    return sorted(entries, key=lambda item: item[0])


def c_string(value: str) -> str:
    return '"' + value.replace("\\", "\\\\").replace('"', '\\"') + '"'


def main() -> int:
    entries = parse_time_zones(TZ_TSX.read_text(encoding="utf-8"))
    max_format = max(len(fmt) for _, fmt in entries)

    lines = [
        "/* Auto-generated by scripts/generate_tz_zones.py — do not edit. */",
        "#pragma once",
        "",
        "#include <stdlib.h>",
        "#include <string.h>",
        "",
        "struct EmsespTzZone {",
        "    const char * label;",
        "    const char * format;",
        "};",
        "",
        f"// Longest POSIX TZ value in the table is {max_format} chars.",
        "static constexpr size_t EMSESP_TZ_ZONE_COUNT = "
        f"{len(entries)};",
        "static const EmsespTzZone EMSESP_TZ_ZONES[EMSESP_TZ_ZONE_COUNT] = {",
    ]
    for label, fmt in entries:
        lines.append(f"    {{{c_string(label)}, {c_string(fmt)}}},")
    lines += [
        "};",
        "",
        "inline int emsesp_tz_zone_cmp(const void * key, const void * element) {",
        "    return strcmp(static_cast<const char *>(key), static_cast<const EmsespTzZone *>(element)->label);",
        "}",
        "",
        "// Returns the POSIX TZ string for an IANA label, or nullptr if unknown.",
        "inline const char * emsesp_tz_format_for_label(const char * label) {",
        "    if (label == nullptr || *label == '\\0') {",
        "        return nullptr;",
        "    }",
        "    const auto * found = static_cast<const EmsespTzZone *>(",
        "        bsearch(label, EMSESP_TZ_ZONES, EMSESP_TZ_ZONE_COUNT, sizeof(EmsespTzZone), emsesp_tz_zone_cmp));",
        "    return found != nullptr ? found->format : nullptr;",
        "}",
        "",
    ]
    OUT_H.write_text("\n".join(lines), encoding="utf-8")
    print(f"Wrote {OUT_H.relative_to(ROOT)} ({len(entries)} zones, max format {max_format})")
    return 0


if __name__ == "__main__":
    sys.exit(main())