#!/usr/bin/env python3
"""Build Efinity raw-HEX images for Ti375C529 persistent Rocket boot."""

import argparse
import hashlib
import json
import re
from pathlib import Path


HEX_BYTE = re.compile(r"[0-9a-fA-F]{2}")


def parse_int(value):
    return int(value, 0)


def read_raw_hex(path):
    data = bytearray()
    with path.open() as source:
        for line_number, line in enumerate(source, 1):
            value = line.strip()
            if not HEX_BYTE.fullmatch(value):
                raise SystemExit(
                    f"{path}:{line_number}: expected one hexadecimal byte per line"
                )
            data.append(int(value, 16))
    return bytes(data)


def write_raw_hex(path, chunks):
    path.parent.mkdir(parents=True, exist_ok=True)
    with path.open("w") as output:
        for chunk in chunks:
            for value in chunk:
                output.write(f"{value:02X}\n")


def sha256(data):
    return hashlib.sha256(data).hexdigest()


def main():
    parser = argparse.ArgumentParser(
        description="Combine an Efinity configuration HEX and Rocket app image"
    )
    parser.add_argument("--config-hex", type=Path, required=True)
    parser.add_argument("--app-bin", type=Path, required=True)
    parser.add_argument("--app-offset", type=parse_int, required=True)
    parser.add_argument("--flash-size", type=parse_int, default=0x04000000)
    parser.add_argument("--nav-context-offset", type=parse_int, required=True)
    parser.add_argument("--ephemeris-offset", type=parse_int, required=True)
    parser.add_argument("--combined-hex", type=Path, required=True)
    parser.add_argument("--app-hex", type=Path, required=True)
    parser.add_argument("--manifest", type=Path, required=True)
    args = parser.parse_args()

    config = read_raw_hex(args.config_hex)
    app = args.app_bin.read_bytes()
    app_end = args.app_offset + len(app)

    if args.app_offset & 0xFFFF:
        raise SystemExit("application offset must be aligned to a 64-KiB sector")
    if len(config) > args.app_offset:
        raise SystemExit(
            f"configuration image (0x{len(config):x} bytes) overlaps application "
            f"at 0x{args.app_offset:x}"
        )
    if app_end > args.flash_size:
        raise SystemExit(
            f"application ends at 0x{app_end:x}, beyond flash size 0x{args.flash_size:x}"
        )
    reserved_size = 2 * 0x10000
    if args.nav_context_offset + reserved_size > args.ephemeris_offset:
        raise SystemExit("navigation context overlaps ephemeris flash region")
    if args.ephemeris_offset + reserved_size > args.flash_size:
        raise SystemExit("ephemeris flash region exceeds device capacity")
    if app_end > args.nav_context_offset:
        raise SystemExit(
            f"application ends at 0x{app_end:x}, overlapping persistent data at "
            f"0x{args.nav_context_offset:x}"
        )

    padding_size = args.app_offset - len(config)
    write_raw_hex(args.app_hex, (app,))
    write_raw_hex(args.combined_hex, (config, bytes([0xFF]) * padding_size, app))

    manifest = {
        "format": "Efinity raw HEX (one byte per line)",
        "flash": "Ti375C529 lower SPI NOR (U47)",
        "flash_size": f"0x{args.flash_size:08x}",
        "configuration": {
            "source": str(args.config_hex),
            "offset": "0x00000000",
            "size": len(config),
            "sha256": sha256(config),
        },
        "application": {
            "source": str(args.app_bin),
            "offset": f"0x{args.app_offset:08x}",
            "size": len(app),
            "sha256": sha256(app),
        },
        "navigation_context": {
            "offset": f"0x{args.nav_context_offset:08x}",
            "size": reserved_size,
        },
        "ephemeris_cache": {
            "offset": f"0x{args.ephemeris_offset:08x}",
            "size": reserved_size,
        },
        "combined": {
            "image": str(args.combined_hex),
            "programmed_length": app_end,
        },
    }
    args.manifest.parent.mkdir(parents=True, exist_ok=True)
    args.manifest.write_text(json.dumps(manifest, indent=2) + "\n")

    print(f"configuration: 0x00000000..0x{len(config) - 1:08x}")
    print(f"application:   0x{args.app_offset:08x}..0x{app_end - 1:08x}")
    print(f"combined HEX:  {args.combined_hex}")


if __name__ == "__main__":
    main()