"""Run the v1 -> v2 codemod against real pinned repositories and audit the result.

Each pinned repo is migrated and pyright-checked on both sides (pristine against the
latest v1 SDK, migrated against this workspace's v2). Every new error must sit on or
near a `# mcp-codemod:` marker; an uncovered error is a silent miss and exits 1.

Usage: uv run --frozen python scripts/codemod-batch-test/run.py [--repo SLUG] [--fresh]
"""

import argparse
import ast
import json
import shutil
import subprocess
import sys
from dataclasses import dataclass
from pathlib import Path

from mcp_codemod._dependencies import update_dependencies
from mcp_codemod._runner import discover
from mcp_codemod._runner import run as run_codemod
from mcp_codemod._transformer import MARKER

HARNESS_DIR = Path(__file__).resolve().parent
WORKSPACE_ROOT = HARNESS_DIR.parents[1]
# Dot-directory: pytest's default norecursedirs keeps cloned repos' test suites out of `./scripts/test`.
WORK_DIR = HARNESS_DIR / ".work"

# Max line distance for an error to still count as explained by a marker.
MARKER_RADIUS = 3

# Rules written off as v2 strictness drift, but only in a file the codemod did not touch and with
# no mcp symbol in the message. `reportAttributeAccessIssue` is absent: a missed removal looks like it.
DRIFT_RULES = frozenset({"reportArgumentType", "reportOptionalSubscript", "reportOptionalMemberAccess"})

# A `reportArgumentType` error naming one of these is a real runtime break on v2, never strictness drift.
DETONATOR_TYPES = ("timedelta", "AnyUrl")

# Rules that carry a break's downstream type propagation rather than its source.
CASCADE_RULES = frozenset({"reportArgumentType", "reportAssignmentType", "reportCallIssue", "reportReturnType"})

# Outside the SDK checkout: inside it, uv resolves the SDK workspace itself and the env would hold v2.
V1_ENV_DIR = Path.home() / ".cache" / "mcp-codemod-batch-test" / "v1env"

V1_ENV_PYPROJECT = """\
[project]
name = "codemod-batch-test-v1-env"
version = "0"
requires-python = ">=3.10"
dependencies = ["mcp[cli,ws]>=1.9,<2"]

# Belt and braces: never resolve as a member of some enclosing workspace.
[tool.uv.workspace]
"""


@dataclass(frozen=True, slots=True)
class Repo:
    slug: str
    url: str
    sha: str
    include: tuple[str, ...]
    note: str


@dataclass(frozen=True, slots=True)
class PyrightError:
    file: str
    line: int
    rule: str
    message: str

    @property
    def key(self) -> tuple[str, str, str]:
        """Line-independent identity, so unrelated baseline noise cancels out."""
        return (self.file, self.rule, self.message)


def _run(command: list[str], *, cwd: Path) -> subprocess.CompletedProcess[str]:
    return subprocess.run(command, cwd=cwd, capture_output=True, text=True, check=False)


def _load_repos(only: str | None) -> list[Repo]:
    raw: object = json.loads((HARNESS_DIR / "repos.json").read_text())
    assert isinstance(raw, list)
    repos: list[Repo] = []
    for entry in raw:
        assert isinstance(entry, dict)
        repo = Repo(
            slug=str(entry["slug"]),
            url=str(entry["url"]),
            sha=str(entry["sha"]),
            include=tuple(str(item) for item in entry["include"]),
            note=str(entry["note"]),
        )
        if only is None or repo.slug == only:
            repos.append(repo)
    return repos


def _ensure_v1_environment() -> Path:
    """Create (once) an environment holding the latest v1 SDK; return its python.

    Fails loudly unless it really holds v1: a v2 baseline would report no migration delta.
    """
    env_dir = V1_ENV_DIR
    python = env_dir / ".venv" / "bin" / "python"
    if not python.is_file():
        env_dir.mkdir(parents=True, exist_ok=True)
        (env_dir / "pyproject.toml").write_text(V1_ENV_PYPROJECT)
        print("setting up the v1 environment (one-time)...")
        sync = _run(["uv", "sync"], cwd=env_dir)
        if sync.returncode != 0:
            sys.exit(f"v1 environment setup failed:\n{sync.stderr}")
    probe = _run([str(python), "-c", "import mcp.types"], cwd=env_dir)
    if probe.returncode != 0:
        sys.exit(f"the v1 environment does not hold a v1 SDK:\n{probe.stderr}")
    return python


def _clone_pinned(repo: Repo, destination: Path, *, fresh: bool) -> None:
    if destination.is_dir():
        if not fresh:
            return
        shutil.rmtree(destination)
    destination.mkdir(parents=True)
    for command in (
        ["git", "init", "-q"],
        ["git", "remote", "add", "origin", repo.url],
        ["git", "fetch", "-q", "--depth", "1", "origin", repo.sha],
        ["git", "checkout", "-q", "FETCH_HEAD"],
    ):
        result = _run(command, cwd=destination)
        if result.returncode != 0:
            sys.exit(f"{repo.slug}: `{' '.join(command)}` failed:\n{result.stderr}")


def _side_roots(repo: Repo, side: Path) -> list[Path]:
    return [side / sub for sub in repo.include] if repo.include else [side]


def _pyright_errors(repo: Repo, *, python: Path, side: Path) -> list[PyrightError] | None:
    """Type-check one side against the env of `python`, or None when pyright dies.

    The config is written into the side's own root with relative includes, so
    nothing outside it is ever scanned.

    `--pythonpath` beats the implicit `VIRTUAL_ENV` that `uv run` exports, which a config `venvPath` does not.
    """
    config = {
        "include": list(repo.include) or ["."],
        "typeCheckingMode": "basic",
    }
    (side / "pyrightconfig.json").write_text(json.dumps(config))
    result = _run(
        ["uv", "run", "--frozen", "pyright", "--project", str(side), "--pythonpath", str(python), "--outputjson"],
        cwd=WORKSPACE_ROOT,
    )
    try:
        output: object = json.loads(result.stdout)
    except json.JSONDecodeError:
        print(f"  pyright produced no JSON (exit {result.returncode}):\n{result.stderr}", file=sys.stderr)
        return None
    assert isinstance(output, dict)
    summary = output.get("summary")
    assert isinstance(summary, dict)
    if not summary.get("filesAnalyzed"):
        # A bad include path makes pyright "succeed" over nothing; fail the repo instead.
        print(f"  pyright analyzed zero files in {side} -- check the include paths", file=sys.stderr)
        return None
    diagnostics = output.get("generalDiagnostics")
    assert isinstance(diagnostics, list)
    errors: list[PyrightError] = []
    for diagnostic in diagnostics:
        assert isinstance(diagnostic, dict)
        if diagnostic.get("severity") != "error":
            continue
        file = str(Path(str(diagnostic["file"])).relative_to(side))
        start = diagnostic["range"]["start"]["line"]
        assert isinstance(start, int)
        errors.append(
            PyrightError(
                file=file,
                line=start + 1,  # pyright lines are zero-based
                rule=str(diagnostic.get("rule", "")),
                message=str(diagnostic["message"]),
            )
        )
    return errors


def _statement_spans(source: str) -> list[tuple[int, int]]:
    """The (lineno, end_lineno) of every statement in a parseable Python file.

    A compound statement contributes only its HEADER lines (up to its first body
    statement): a marker above a `with` covers the multi-line call in its header,
    never the hundreds of lines inside a def or class body.
    """
    try:
        tree = ast.parse(source)
    except SyntaxError:
        return []
    spans: list[tuple[int, int]] = []
    for node in ast.walk(tree):
        if not isinstance(node, ast.stmt):
            continue
        end = node.end_lineno or node.lineno
        body = getattr(node, "body", None)
        if isinstance(body, list) and body and isinstance(body[0], ast.stmt):
            end = min(end, body[0].lineno - 1)
        spans.append((node.lineno, end))
    return spans


def _collect_markers(roots: list[Path], side: Path) -> dict[str, list[tuple[int, int]]]:
    """Every `# mcp-codemod:` line in the migrated tree, by file, as covered spans.

    A marker covers `MARKER_RADIUS` around itself plus any statement starting within that radius below it.
    """
    markers: dict[str, list[tuple[int, int]]] = {}
    needle = f"# {MARKER}:"
    for root in roots:
        candidates = [path for path in root.rglob("*") if path.suffix == ".py" or path.name == "pyproject.toml"]
        candidates += list(root.rglob("requirements*.txt"))
        for path in candidates:
            try:
                source = path.read_bytes().decode("utf-8")
            except (OSError, UnicodeDecodeError):
                continue
            lines = source.splitlines()
            hits = [number for number, line in enumerate(lines, start=1) if needle in line]
            if not hits:
                continue
            spans = _statement_spans(source) if path.suffix == ".py" else []
            covered: list[tuple[int, int]] = []
            for hit in hits:
                end = hit + MARKER_RADIUS
                for start, stop in spans:
                    if hit < start <= hit + MARKER_RADIUS:
                        end = max(end, stop)
                covered.append((hit - MARKER_RADIUS, end))
            markers[str(path.relative_to(side))] = covered
    return markers


def _audit_repo(repo: Repo, *, v1_python: Path, fresh: bool) -> tuple[dict[str, object], int] | None:
    print(f"\n=== {repo.slug} ({repo.note})")
    pristine = WORK_DIR / "repos" / repo.slug / "pristine"
    migrated = WORK_DIR / "repos" / repo.slug / "migrated"
    _clone_pinned(repo, pristine, fresh=fresh)

    if migrated.is_dir():
        shutil.rmtree(migrated)
    shutil.copytree(pristine, migrated, ignore=shutil.ignore_patterns(".git"))

    roots = _side_roots(repo, migrated)
    report = run_codemod(discover(roots), write=True)
    dependency_reports = update_dependencies(roots, write=True)
    severities = report.diagnostics
    rewritten_files = {str(file.path.relative_to(migrated)) for file in report.changed}
    print(
        f"  codemod: {len(report.changed)} of {len(report.files)} files rewritten, "
        f"{severities['manual'] + severities['review']} flagged sites, "
        f"{sum(1 for dependency in dependency_reports if dependency.changed)} dependency files updated"
    )

    baseline = _pyright_errors(repo, python=v1_python, side=pristine)
    post = _pyright_errors(repo, python=WORKSPACE_ROOT / ".venv" / "bin" / "python", side=migrated)
    if baseline is None or post is None:
        return None
    baseline_keys = {error.key for error in baseline}
    new_errors = [error for error in post if error.key not in baseline_keys]
    resolved = len(baseline) - len([error for error in baseline if error.key in {e.key for e in post}])

    markers = _collect_markers(roots, migrated)
    actionable: list[PyrightError] = []
    drift: list[PyrightError] = []
    cascade: list[PyrightError] = []
    for error in new_errors:
        spans = markers.get(error.file, [])
        if any(start <= error.line <= end for start, end in spans):
            continue
        # A break's source always errors without "Unknown" in its message, so
        # "Unknown" only appears in downstream propagation -- and in a marked file
        # the roots are the marked ones. Detonators stay actionable regardless.
        is_detonator = any(f'of type "{detonator}"' in error.message for detonator in DETONATOR_TYPES)
        if "Unknown" in error.message and spans and not is_detonator and error.rule in CASCADE_RULES:
            cascade.append(error)
            continue
        if (
            error.file not in rewritten_files
            and "mcp" not in error.message.lower()
            and error.rule in DRIFT_RULES
            and not any(f'of type "{detonator}"' in error.message for detonator in DETONATOR_TYPES)
        ):
            drift.append(error)
        else:
            actionable.append(error)

    covered = len(new_errors) - len(actionable) - len(drift) - len(cascade)
    print(
        f"  pyright: {len(baseline)} baseline errors, {len(new_errors)} new after migration "
        f"({resolved} resolved): {covered} covered by markers, {len(cascade)} marked-break cascade, "
        f"{len(drift)} v2 strictness drift"
    )
    for error in actionable:
        print(f"  UNCOVERED  {error.file}:{error.line}  [{error.rule}] {error.message.splitlines()[0]}")

    result: dict[str, object] = {
        "slug": repo.slug,
        "sha": repo.sha,
        "files_rewritten": len(report.changed),
        "files_total": len(report.files),
        "flagged_sites": severities["manual"] + severities["review"],
        "baseline_errors": len(baseline),
        "new_errors": len(new_errors),
        "covered_by_markers": covered,
        "strictness_drift": [
            {"file": error.file, "line": error.line, "rule": error.rule, "message": error.message} for error in drift
        ],
        "uncovered": [
            {"file": error.file, "line": error.line, "rule": error.rule, "message": error.message}
            for error in actionable
        ],
    }
    return result, len(actionable)


def main() -> int:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--repo", help="run a single repository by slug")
    parser.add_argument("--fresh", action="store_true", help="re-clone repositories even when present")
    args = parser.parse_args()

    repos = _load_repos(args.repo)
    if not repos:
        sys.exit(f"no repository matches {args.repo!r}")
    WORK_DIR.mkdir(exist_ok=True)
    v1_python = _ensure_v1_environment()

    results: list[dict[str, object]] = []
    total_uncovered = 0
    for repo in repos:
        audited = _audit_repo(repo, v1_python=v1_python, fresh=args.fresh)
        if audited is not None:
            result, uncovered = audited
            results.append(result)
            total_uncovered += uncovered

    results_dir = WORK_DIR / "results"
    results_dir.mkdir(exist_ok=True)
    for result in results:
        (results_dir / f"{result['slug']}.json").write_text(json.dumps(result, indent=2) + "\n")

    print(f"\n{len(results)} repositories audited; {total_uncovered} uncovered new errors.")
    return 1 if total_uncovered or len(results) != len(repos) else 0


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