#!/usr/bin/env python3
"""Copy 40250 sources into the port mirror (extension/src/port/<Lib>/<File>) with mechanical edits only.

  port_copy.py copy <rel> [<rel>...] [--force]   write the mechanical copy (refuses to overwrite without --force)
  port_copy.py diff [<rel>...]                   show the manual edits: port file vs its mechanical copy
                                                 (no args: every mirrored 40250 file that differs)

`<rel>` is a reference path such as `GameLib/ActorInstance.h`, matched case-insensitively.

Mechanical edits, and nothing else:
  - CP949 is decoded and written as UTF-8 (comments are Korean). A non-ASCII string or character
    literal would change bytes at runtime, so its non-ASCII characters are written as their CP949
    bytes in 3-digit octal escapes (`"\301\326..."`): the compiled bytes stay those of 40250.
  - CRLF becomes LF.
  - `#include "..."` paths get the on-disk case of the file they name (40250 builds on a
    case-insensitive file system and writes `../eterLib/StdAfx.h`, `Parser.h` for `parser.h`, ...),
    keeping the relative form, so the original include resolves the same way on every platform.
Everything else in a port file that differs from this copy is a manual edit, marked `// PORT:`.
"""

from __future__ import annotations

import argparse
import difflib
import re
import sys
from pathlib import Path

import refroot  # script directory is on sys.path when run directly

REPO = refroot.repo_root()
PORT = REPO / "extension" / "src" / "port"
INCLUDE = re.compile(r'^(\s*#\s*include\s*")([^"]+)(")', re.M)
LITERAL = re.compile(r'"(?:\\.|[^"\\\n])*"|\'(?:\\.|[^\'\\\n])*\'')
COMMENT = re.compile(r"//[^\n]*|/\*.*?\*/", re.S)


def ref_index(ref: Path) -> dict[str, Path]:
    return {p.relative_to(ref).as_posix().lower(): p for p in ref.rglob("*") if p.is_file()}


def canonical(ref: Path, index: dict[str, Path], path: Path) -> str:
    return index[path.relative_to(ref).as_posix().lower()].relative_to(ref).as_posix()


def resolve(ref: Path, index: dict[str, Path], rel: str) -> Path:
    hit = index.get(rel.replace("\\", "/").lower())
    if not hit:
        raise SystemExit(f"{rel}: not in the 40250 reference tree")
    return hit


def fix_include(ref: Path, index: dict[str, Path], src: Path, target: str) -> str:
    base = src.parent.relative_to(ref).as_posix()
    parts = [] if base == "." else base.split("/")
    for piece in target.replace("\\", "/").split("/"):
        if piece == "..":
            if not parts:
                return target
            parts.pop()
        elif piece != ".":
            parts.append(piece)
    hit = index.get("/".join(parts).lower())
    if not hit:
        return target  # unresolved (commented-out or absent in 40250): leave untouched
    real = hit.relative_to(ref).as_posix().split("/")
    # Keep the original shape: same number of `..` and segments, only the case changes.
    kept = [p for p in target.replace("\\", "/").split("/") if p in ("..", ".")]
    tail = real[len(real) - (len(target.replace("\\", "/").split("/")) - len(kept)):]
    return "/".join(kept + tail)


def mechanical(ref: Path, index: dict[str, Path], src: Path) -> str:
    raw = src.read_bytes()
    try:
        text = raw.decode("cp949")
    except UnicodeDecodeError as e:
        raise SystemExit(f"{src.relative_to(ref)}: not CP949 ({e})")
    text = text.replace("\r\n", "\n").lstrip("")
    code = COMMENT.sub(lambda m: " " * len(m.group(0)), text)
    # Literals are found with comments blanked out; offsets are the same in `text`.
    for m in reversed(list(LITERAL.finditer(code))):
        if not m.group(0).isascii():
            escaped = "".join(c if c.isascii() else "".join(f"\\{b:03o}" for b in c.encode("cp949"))
                              for c in m.group(0))
            text = text[:m.start()] + escaped + text[m.end():]
    return INCLUDE.sub(lambda m: m.group(1) + fix_include(ref, index, src, m.group(2)) + m.group(3), text)


def cmd_copy(args) -> int:
    ref = refroot.reference_root()
    index = ref_index(ref)
    for rel in args.rel:
        src = resolve(ref, index, rel)
        dst = PORT / canonical(ref, index, src)
        if dst.exists() and not args.force:
            print(f"skip {dst.relative_to(REPO)} (exists; --force overwrites manual edits)")
            continue
        dst.parent.mkdir(parents=True, exist_ok=True)
        dst.write_text(mechanical(ref, index, src), encoding="utf-8")
        print(f"copy {dst.relative_to(REPO)}")
    return 0


def cmd_diff(args) -> int:
    ref = refroot.reference_root()
    index = ref_index(ref)
    if args.rel:
        pairs = [(resolve(ref, index, r), PORT / canonical(ref, index, resolve(ref, index, r))) for r in args.rel]
    else:
        pairs = []
        for dst in sorted(PORT.rglob("*")):
            key = dst.relative_to(PORT).as_posix().lower()
            if dst.is_file() and key in index and not key.startswith("common/"):
                pairs.append((index[key], dst))
    changed = 0
    for src, dst in pairs:
        if not dst.exists():
            print(f"missing {dst.relative_to(REPO)}")
            continue
        want = mechanical(ref, index, src).splitlines(keepends=True)
        have = dst.read_text(encoding="utf-8").splitlines(keepends=True)
        diff = list(difflib.unified_diff(want, have, f"40250/{src.relative_to(ref).as_posix()}",
                                         dst.relative_to(REPO).as_posix()))
        if diff:
            changed += 1
            sys.stdout.writelines(diff)
    print(f"{changed} of {len(pairs)} file(s) with manual edits", file=sys.stderr)
    return 0


def main() -> int:
    ap = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
    sub = ap.add_subparsers(dest="cmd", required=True)
    c = sub.add_parser("copy")
    c.add_argument("rel", nargs="+")
    c.add_argument("--force", action="store_true")
    d = sub.add_parser("diff")
    d.add_argument("rel", nargs="*")
    args = ap.parse_args()
    return {"copy": cmd_copy, "diff": cmd_diff}[args.cmd](args)


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