#!/usr/bin/env python3
"""
convert.py — Convert a single .txt show file to an Arduino header.

Use this to preview or test a single show.
For the full workflow (all shows + regenerate shows.h), use convert_all.py.

Usage:
    python converter/convert.py path/to/show.txt

Output:
    show_<name>.h  written to the current directory.
    Move it to arduino/cosplay_lights/ then run: make upload

Show file format:
    Each step is one line:  #RRGGBB, duration_ms
    Lines starting with // are comments and are ignored.
    Blank lines are ignored.

    duration_ms controls how long the fade from the PREVIOUS color takes:
        0       = instant switch (no fade)
        500     = half-second fade
        5000    = five-second slow fade

    To hold a color, add a second step with the same color and the hold time as duration:
        #FF0000,    0   // snap to red
        #FF0000, 2000   // hold red for 2 seconds
        #0000FF, 3000   // fade to blue over 3 seconds

SPDX-License-Identifier: BSD-2-Clause
"""

import sys
import re
from pathlib import Path

STEP_PATTERN = re.compile(r'^\s*#([0-9A-Fa-f]{6})\s*,\s*(\d+)')


def filename_to_symbol(stem: str) -> str:
    """Convert a filename stem to an uppercase C array symbol."""
    clean = re.sub(r'[^a-zA-Z0-9]', '_', stem)
    return "SHOW_" + clean.upper()


def hex_to_rgb(hex_str: str) -> tuple[int, int, int]:
    return int(hex_str[0:2], 16), int(hex_str[2:4], 16), int(hex_str[4:6], 16)


def parse_show(filepath: Path) -> list[tuple[int, int, int, int]]:
    """
    Parse a .txt show file. Returns list of (r, g, b, duration_ms) tuples.
    Raises ValueError on malformed lines.
    """
    steps = []
    with open(filepath) as f:
        for lineno, raw_line in enumerate(f, 1):
            line = raw_line.split("//")[0].strip()
            if not line:
                continue
            match = STEP_PATTERN.match(line)
            if not match:
                raise ValueError(
                    f"Line {lineno}: expected '#RRGGBB, duration_ms' "
                    f"but got: {raw_line.rstrip()!r}"
                )
            r, g, b  = hex_to_rgb(match.group(1))
            duration = int(match.group(2))
            steps.append((r, g, b, duration))
    if not steps:
        raise ValueError("Show file contains no steps.")
    return steps


def render_header(steps: list, source_name: str, symbol: str) -> str:
    """Render parsed steps as a C++ header file string."""
    lines = [
        f"// Generated by convert.py from: {source_name}",
        "// Do not edit manually — edit the .txt file instead.",
        "// SPDX-License-Identifier: BSD-2-Clause",
        "",
        "#pragma once",
        '#include "lightshow_format.h"',
        "",
        f"const Step {symbol}[] PROGMEM = {{",
    ]
    for r, g, b, dur in steps:
        hex_color = f"#{r:02X}{g:02X}{b:02X}"
        lines.append(f"    {{{r:3d}, {g:3d}, {b:3d}, {dur:5d}}},  // {hex_color}, {dur}ms")
    lines += [
        "};",
        f"const uint16_t {symbol}_LENGTH = {len(steps)};",
        "",
    ]
    return "\n".join(lines)


def main() -> None:
    if len(sys.argv) != 2:
        print(__doc__)
        sys.exit(1)

    source_path = Path(sys.argv[1])
    if not source_path.exists():
        print(f"Error: file not found: {source_path}")
        sys.exit(1)

    try:
        steps = parse_show(source_path)
    except ValueError as e:
        print(f"Error: {e}")
        sys.exit(1)

    symbol      = filename_to_symbol(source_path.stem)
    header_text = render_header(steps, source_path.name, symbol)
    output_path = Path(f"show_{source_path.stem}.h")
    output_path.write_text(header_text, encoding="utf-8")

    print(f"OK  {len(steps)} steps  →  {output_path}")
    print(f"    Move to 'arduino/cosplay_lights/' then run 'make upload'.")
    print(f"    Or run 'make shows' to convert all shows at once.")


if __name__ == "__main__":
    main()