#!/usr/bin/env python3
import argparse
import json
import os
import re
from datetime import datetime
from pathlib import Path

def flatten(d, prefix=""):
    for k, v in d.items():
        key = f"{prefix}.{k}" if prefix else k
        if isinstance(v, dict):
            yield from flatten(v, key)
        else:
            yield key

def gather_files(src_dir, exts=(".ts", ".tsx", ".js", ".jsx", ".html", ".vue", ".json")):
    for root, _, files in os.walk(src_dir):
        parts = root.split(os.sep)
        if "node_modules" in parts or ".git" in parts:
            continue
        for fn in files:
            if fn.endswith(exts):
                yield Path(root) / fn

def find_usages(keys, files):
    usages = {k: [] for k in keys}
    # Precompile patterns for speed
    patterns = {k: re.compile(r"\bm\." + re.escape(k) + r"\s*\(") for k in keys}
    for file in files:
        try:
            text = file.read_text(encoding="utf-8")
        except Exception:
            continue
        lines = text.splitlines()
        for i, line in enumerate(lines, start=1):
            for k, pat in patterns.items():
                if pat.search(line):
                    usages[k].append({
                        "file": str(file),
                        "line": i,
                        "text": line.strip()
                    })
    return usages

def main():
    p = argparse.ArgumentParser(description="Generate JSON report of localization key usage (m.key_name_here()).")
    p.add_argument("--en", default="../ui/localization/messages/en.json", help="path to en.json")
    p.add_argument("--src", default="../ui", help="root source directory to scan")
    p.add_argument("--out", default="../reports/localization_report.json", help="output report file")
    args = p.parse_args()

    en_path = Path(args.en)
    if not en_path.is_file():
        print(f"en.json not found: {en_path}", flush=True)
        raise SystemExit(2)

    with en_path.open(encoding="utf-8") as f:
        payload = json.load(f)

    keys = sorted(list(flatten(payload)))
    files = list(gather_files(args.src))
    usages = find_usages(keys, files)

    report = {
        "generated_at": datetime.utcnow().isoformat() + "Z",
        "en_json": str(en_path),
        "src_root": args.src,
        "total_keys": len(keys),
        "keys": {}
    }

    unused_count = 0
    for k in keys:
        occ = usages.get(k, [])
        used = bool(occ)
        if not used:
            unused_count += 1
        report["keys"][k] = {
            "used": used,
            "occurrences": occ
        }

    report["unused_count"] = unused_count
    report["unused_keys"] = [k for k, v in report["keys"].items() if not v["used"]]

    out_path = Path(args.out)
    out_path.parent.mkdir(parents=True, exist_ok=True)
    with out_path.open("w", encoding="utf-8") as f:
        json.dump(report, f, indent=2, ensure_ascii=False)

    print(f"Report written to {out_path}")
    print(f"Total keys: {report['total_keys']}, Unused: {report['unused_count']}")

if __name__ == "__main__":
    main()