"""
patch_port.py — Rewrites the port in main.py to 7860 (HuggingFace Spaces).

Handles all common FastAPI/uvicorn port patterns:
  - uvicorn.run(app, host="...", port=XXXX)
  - uvicorn.run("main:app", host="...", port=XXXX)
  - port = XXXX  (bare assignment)
  - --port XXXX  (CLI string inside code)
  - PORT env var fallback patterns
"""

import re
import sys
import shutil
from pathlib import Path

TARGET_PORT = 7860
MAIN_FILE   = Path(__file__).parent / "main.py"
BACKUP_FILE = MAIN_FILE.with_suffix(".py.bak")

# ── Regex patterns to match & replace ────────────────────────────────────────
PATTERNS = [
    # uvicorn.run(..., port=11235, ...)  — any existing port number
    (r'(port\s*=\s*)\d{4,5}', rf'\g<1>{TARGET_PORT}'),

    # uvicorn.run("main:app", ..., port=11235)
    (r'("port"\s*:\s*)\d{4,5}', rf'\g<1>{TARGET_PORT}'),

    # os.environ.get("PORT", "11235")
    (r'(os\.environ\.get\(["\']PORT["\']\s*,\s*["\'])\d{4,5}(["\'])', rf'\g<1>{TARGET_PORT}\g<2>'),

    # PORT = 11235
    (r'^(PORT\s*=\s*)\d{4,5}', rf'\g<1>{TARGET_PORT}', re.MULTILINE),
]

def patch(file: Path) -> bool:
    if not file.exists():
        print(f"[patch_port] ERROR: {file} not found.", file=sys.stderr)
        sys.exit(1)

    original = file.read_text(encoding="utf-8")
    patched  = original
    changes  = 0

    for entry in PATTERNS:
        pattern, replacement = entry[0], entry[1]
        flags = entry[2] if len(entry) == 3 else 0
        new, n = re.subn(pattern, replacement, patched, flags=flags)
        if n:
            changes += n
            patched = new

    if changes == 0:
        print(f"[patch_port] No port patterns found in {file}.")
        print(f"[patch_port] Please verify main.py manually sets port={TARGET_PORT}.")
        # Don't fail — app might already be correct or uses env var
        return False

    # Write backup then patched file
    shutil.copy(file, BACKUP_FILE)
    file.write_text(patched, encoding="utf-8")
    print(f"[patch_port] ✅ {changes} replacement(s) made in {file}")
    print(f"[patch_port] Backup saved to {BACKUP_FILE}")
    return True

if __name__ == "__main__":
    patch(MAIN_FILE)