#!/usr/bin/env python3
"""Generate targets_generated.h from a resolved target table.

The header holds each target's RVA, length and 20-byte FNV-1a fingerprint as a
named struct field, plus the build's version. The hook library checks the
fingerprint against the running libil2cpp.so before arming, so a table can only
ever be applied to the build it was resolved from.

Usage: gen_targets_header.py <targets/NAME-CODE.json> <out/targets_generated.h>
"""
import json
import sys
from pathlib import Path


def main():
    if len(sys.argv) != 3:
        raise SystemExit("usage: gen_targets_header.py <table.json> <out.h>")
    table = json.loads(Path(sys.argv[1]).read_text(encoding="utf-8"))
    ids = list(table["targets"].keys())

    lines = [
        "// Generated by scripts/gen_targets_header.py -- do not edit.",
        f"// Build {table['versionName']} / versionCode {table['versionCode']}",
        f"// libil2cpp.so sha256 {table['il2cppSha256']}",
        "#ifndef DORKNET_QUEST_TARGETS_GENERATED_H",
        "#define DORKNET_QUEST_TARGETS_GENERATED_H",
        "#include <stdint.h>",
        "",
        f'#define DN_TARGET_VERSION_NAME "{table["versionName"]}"',
        f'#define DN_TARGET_VERSION_CODE "{table["versionCode"]}"',
        f"#define DN_HOOK_BYTES {table['hookBytes']}",
        "",
        "typedef struct { const char *id; uint32_t rva; uint64_t fingerprint; uint32_t length; } DnTarget;",
        "",
        "typedef struct {",
    ]
    for tid in ids:
        lines.append(f"    DnTarget {tid};")
    lines.append("} DnTargets;")
    lines.append("")
    lines.append("static const DnTargets dn_targets = {")
    for tid in ids:
        e = table["targets"][tid]
        length = e["length"] if e["length"] is not None else 0
        lines.append(
            f'    .{tid} = {{ "{tid}", {e["rva"]:#x}u, {e["fingerprint"]}ull, {length}u }},')
    lines.append("};")
    lines.append("")
    lines.append("#endif")
    Path(sys.argv[2]).write_text("\n".join(lines) + "\n", encoding="utf-8")
    print(f"wrote {sys.argv[2]} ({len(ids)} targets)")


if __name__ == "__main__":
    main()