"""Generate components/samsung_vfd/charmaps.h from Python's code page codecs.

Each table lists the Unicode code point shown for bytes 0x80..0xFF in one of
the display's CG-ROM fonts (datasheet section 6), or 0 where there is none.
CP10 (for DP86-20) has no standard codec, so it gets no table.

Run from the repo root:  python tools/gen_charmaps.py
"""

from pathlib import Path

# Same order as the ESC t n argument (datasheet 5.4.18).
TABLES = [
    ("PC437", "cp437"),
    ("PC850", "cp850"),
    ("PC866", "cp866"),
    ("PC737", "cp737"),
    ("PC775", "cp775"),
    ("CP10", None),
    ("PC864", "cp864"),
    ("PC852", "cp852"),
]

OUT = Path(__file__).resolve().parent.parent / "components" / "samsung_vfd" / "charmaps.h"


def high_half(codec):
    points = []
    for b in range(0x80, 0x100):
        try:
            ch = bytes([b]).decode(codec)
        except UnicodeDecodeError:
            ch = ""
        points.append(ord(ch) if len(ch) == 1 else 0)
    return points


def main():
    lines = [
        "// Generated by tools/gen_charmaps.py -- do not edit.",
        "#pragma once",
        "",
        "#include <cstdint>",
        "",
        "namespace esphome {",
        "namespace samsung_vfd {",
        "",
    ]
    names = []
    for name, codec in TABLES:
        if codec is None:
            names.append("nullptr")
            continue
        ident = f"CHARMAP_{name}"
        names.append(ident)
        pts = high_half(codec)
        lines.append(f"// {name} ({codec}), bytes 0x80..0xFF")
        lines.append(f"static const uint16_t {ident}[128] = {{")
        for i in range(0, 128, 8):
            row = ", ".join(f"0x{p:04X}" for p in pts[i : i + 8])
            lines.append(f"    {row},  // 0x{0x80 + i:02X}")
        lines.append("};")
        lines.append("")
    lines.append("// Indexed by CodeTable (the ESC t argument); nullptr = no mapping known.")
    lines.append(f"static const uint16_t *const CHARMAPS[{len(TABLES)}] = {{")
    for (name, _), ident in zip(TABLES, names):
        lines.append(f"    {ident},  // {name}")
    lines.append("};")
    lines.append("")
    lines.append("}  // namespace samsung_vfd")
    lines.append("}  // namespace esphome")
    lines.append("")
    OUT.write_text("\n".join(lines), encoding="utf-8", newline="\n")
    print(f"wrote {OUT}")


if __name__ == "__main__":
    main()