#!/usr/bin/env python3
import argparse
import importlib.util
import json
import pathlib
import sys
from typing import Any

HELPER_PATH = pathlib.Path(__file__).with_name("prepare-cv-approved-fixtures.py")
HELPER_SPEC = importlib.util.spec_from_file_location("prepare_cv_approved_fixtures", HELPER_PATH)
if HELPER_SPEC is None or HELPER_SPEC.loader is None:
    raise RuntimeError(f"Unable to load helper script: {HELPER_PATH}")
HELPER_MODULE = importlib.util.module_from_spec(HELPER_SPEC)
HELPER_SPEC.loader.exec_module(HELPER_MODULE)
normalize_fixture = HELPER_MODULE.normalize_fixture


def load_json(path: pathlib.Path) -> Any:
    return json.loads(path.read_text(encoding="utf-8", errors="replace"))


def diff_values(expected: Any, actual: Any, path: str = "$") -> list[dict[str, Any]]:
    diffs: list[dict[str, Any]] = []

    if type(expected) is not type(actual):
        diffs.append({"path": path, "expected": expected, "actual": actual, "kind": "type-mismatch"})
        return diffs

    if isinstance(expected, dict):
        expected_keys = set(expected.keys())
        actual_keys = set(actual.keys())
        for key in sorted(expected_keys | actual_keys):
            child_path = f"{path}.{key}"
            if key not in expected:
                diffs.append({"path": child_path, "expected": None, "actual": actual[key], "kind": "unexpected-key"})
                continue
            if key not in actual:
                diffs.append({"path": child_path, "expected": expected[key], "actual": None, "kind": "missing-key"})
                continue
            diffs.extend(diff_values(expected[key], actual[key], child_path))
        return diffs

    if isinstance(expected, list):
        if len(expected) != len(actual):
            diffs.append({"path": path, "expected": f"len={len(expected)}", "actual": f"len={len(actual)}", "kind": "length-mismatch"})
        for index, (expected_item, actual_item) in enumerate(zip(expected, actual)):
            diffs.extend(diff_values(expected_item, actual_item, f"{path}[{index}]"))
        return diffs

    if expected != actual:
        diffs.append({"path": path, "expected": expected, "actual": actual, "kind": "value-mismatch"})
    return diffs


def summarize_sections(diffs: list[dict[str, Any]]) -> dict[str, int]:
    sections: dict[str, int] = {}
    for diff in diffs:
        path = diff["path"]
        remainder = path[2:] if path.startswith('$.') else path
        head = remainder.split('.', 1)[0].split('[', 1)[0]
        sections[head] = sections.get(head, 0) + 1
    return dict(sorted(sections.items(), key=lambda item: (-item[1], item[0])))


def render_markdown(results: list[dict[str, Any]], missing_expected: list[str], missing_actual: list[str], approved_dir: pathlib.Path, actual_dir: pathlib.Path) -> str:
    total = len(results)
    matched = sum(1 for result in results if result["diffCount"] == 0)
    lines = [
        "# CV fixture comparison report",
        "",
        f"- Approved fixtures: `{approved_dir}`",
        f"- Actual outputs: `{actual_dir}`",
        f"- Compared files: {total}",
        f"- Exact matches: {matched}",
        f"- Files with differences: {total - matched}",
        "",
    ]

    if missing_expected:
        lines.append("## Missing approved fixtures")
        lines.extend(f"- {name}" for name in missing_expected)
        lines.append("")

    if missing_actual:
        lines.append("## Missing actual outputs")
        lines.extend(f"- {name}" for name in missing_actual)
        lines.append("")

    lines.append("## File results")
    lines.append("")
    lines.append("| File | Diffs | Top sections |")
    lines.append("|---|---:|---|")
    for result in results:
        section_summary = ", ".join(f"{key}:{value}" for key, value in result["sectionCounts"].items()) or "—"
        lines.append(f"| {result['file']} | {result['diffCount']} | {section_summary} |")

    lines.append("")
    lines.append("## Detailed mismatches")
    lines.append("")
    for result in results:
        if result["diffCount"] == 0:
            continue
        lines.append(f"### {result['file']}")
        for diff in result["diffs"][:50]:
            lines.append(f"- `{diff['path']}` ({diff['kind']})")
            lines.append(f"  - expected: `{json.dumps(diff['expected'], ensure_ascii=False)}`")
            lines.append(f"  - actual: `{json.dumps(diff['actual'], ensure_ascii=False)}`")
        if result["diffCount"] > 50:
            lines.append(f"- … {result['diffCount'] - 50} more differences omitted")
        lines.append("")

    return "\n".join(lines)


def main() -> int:
    parser = argparse.ArgumentParser(description="Compare actual CV extractor outputs against approved fixtures.")
    parser.add_argument("--approved", default="/home/pi/cvs/approved-jsons", help="Directory containing approved fixture JSON files")
    parser.add_argument("--actual", required=True, help="Directory containing actual extractor output JSON files")
    parser.add_argument("--output", help="Directory to write comparison artifacts. Defaults to <actual>/../comparison")
    args = parser.parse_args()

    approved_dir = pathlib.Path(args.approved)
    actual_dir = pathlib.Path(args.actual)
    output_dir = pathlib.Path(args.output) if args.output else actual_dir.parent / "comparison"

    if not approved_dir.is_dir():
        print(f"Approved fixture directory not found: {approved_dir}", file=sys.stderr)
        return 1
    if not actual_dir.is_dir():
        print(f"Actual output directory not found: {actual_dir}", file=sys.stderr)
        return 1

    approved_files = {path.name: path for path in approved_dir.glob("*.json")}
    actual_files = {path.name: path for path in actual_dir.glob("*.json")}

    common_names = sorted(set(approved_files) & set(actual_files))
    missing_expected = sorted(set(actual_files) - set(approved_files))
    missing_actual = sorted(set(approved_files) - set(actual_files))

    results: list[dict[str, Any]] = []
    for name in common_names:
        expected = normalize_fixture(load_json(approved_files[name]))
        actual = normalize_fixture(load_json(actual_files[name]))
        diffs = diff_values(expected, actual)
        results.append({
            "file": name,
            "diffCount": len(diffs),
            "sectionCounts": summarize_sections(diffs),
            "diffs": diffs,
        })

    output_dir.mkdir(parents=True, exist_ok=True)
    (output_dir / "comparison.json").write_text(json.dumps({
        "approvedDir": str(approved_dir),
        "actualDir": str(actual_dir),
        "comparedFiles": len(results),
        "missingApprovedFixtures": missing_expected,
        "missingActualOutputs": missing_actual,
        "results": results,
    }, indent=2, ensure_ascii=False) + "\n", encoding="utf-8")
    (output_dir / "comparison.md").write_text(render_markdown(results, missing_expected, missing_actual, approved_dir, actual_dir) + "\n", encoding="utf-8")

    print(f"Comparison JSON: {output_dir / 'comparison.json'}")
    print(f"Comparison markdown: {output_dir / 'comparison.md'}")
    print(f"Compared files: {len(results)}")
    print(f"Files with differences: {sum(1 for result in results if result['diffCount'] > 0)}")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())