#!/usr/bin/env python3
"""Cut a new raw generation or processed schema version for the geant_steps
dataset tree (see scripts/migrate_geant_steps.py for the layout):

    raw/<kind>/<gen>/<detector>/shard-NNN.root
    processed/<kind>/<gen>/<schema>/<detector>/shard-NNN.parquet
    pools/<detector>/<pool>.manifest

`gen` bumps when the underlying ROOT changes (geometry/physics-list/macro).
`schema` bumps when the parquet export (steps_to_parquet.py or similar)
changes, and is scoped to its gen — a new gen always starts back at schema1.

Creates the new (empty) target directory and appends a dated, reasoned entry
to VERSIONS.md. Defaults to a dry run; pass --execute to apply.

Usage:
    bump_dataset_version.py bump-gen --kind steps --reason "switched EM physics list"
    bump_dataset_version.py bump-schema --kind steps --gen gen1 --reason "added e_sec column"
    bump_dataset_version.py update-manifest pools/pbwo4/full.manifest [--schema schema2]
    bump_dataset_version.py create-manifest --output pools/pbwo4/train.manifest a.parquet b.parquet
    bump_dataset_version.py status
"""

import argparse
import datetime as dt
import os
import re
import subprocess
from pathlib import Path

GEN_RE = re.compile(r"^gen(\d+)$")
SCHEMA_RE = re.compile(r"^schema(\d+)$")


def _max_index(parent: Path, pattern: re.Pattern) -> int:
    """Highest N across child dir names matching *pattern* (0 if none/missing)."""
    if not parent.is_dir():
        return 0
    best = 0
    for child in parent.iterdir():
        m = pattern.match(child.name)
        if m and child.is_dir():
            best = max(best, int(m.group(1)))
    return best


def _git_user_name() -> str | None:
    try:
        out = subprocess.run(
            ["git", "config", "user.name"], capture_output=True, text=True, timeout=2
        )
    except OSError:
        return None
    name = out.stdout.strip()
    return name or None


def plan_bump_gen(
    root: Path, kind: str, reason: str, by: str | None, date: str
) -> tuple[list[Path], str]:
    """New gen tag is one past the highest seen under raw/ or processed/ for *kind*
    — checking both, since a gen can exist in one tree before the other catches up."""
    next_gen = (
        max(
            _max_index(root / "raw" / kind, GEN_RE),
            _max_index(root / "processed" / kind, GEN_RE),
        )
        + 1
    )
    gen_tag = f"gen{next_gen}"
    new_dirs = [
        root / "raw" / kind / gen_tag,
        root / "processed" / kind / gen_tag / "schema1",
    ]
    by_suffix = f" ({by})" if by else ""
    log_line = f"- `{gen_tag}` (kind={kind}) — {date} — {reason}{by_suffix}"
    return new_dirs, log_line


def plan_bump_schema(
    root: Path, kind: str, gen_tag: str, reason: str, by: str | None, date: str
) -> tuple[list[Path], str]:
    if not GEN_RE.match(gen_tag):
        raise SystemExit(f"error: --gen must look like 'genN', got {gen_tag!r}")
    raw_gen_dir = root / "raw" / kind / gen_tag
    processed_gen_dir = root / "processed" / kind / gen_tag
    if not raw_gen_dir.is_dir() and not processed_gen_dir.is_dir():
        raise SystemExit(
            f"error: {gen_tag} doesn't exist yet for kind={kind} — run bump-gen first"
        )
    next_schema = _max_index(processed_gen_dir, SCHEMA_RE) + 1
    schema_tag = f"schema{next_schema}"
    new_dirs = [processed_gen_dir / schema_tag]
    by_suffix = f" ({by})" if by else ""
    log_line = f"- `{gen_tag}`/`{schema_tag}` (kind={kind}) — {date} — {reason}{by_suffix}"
    return new_dirs, log_line


def apply_bump(root: Path, new_dirs: list[Path], log_line: str) -> None:
    for d in new_dirs:
        d.mkdir(parents=True, exist_ok=True)
    versions_path = root / "VERSIONS.md"
    if not versions_path.exists():
        versions_path.write_text("# Dataset versions\n\n")
    with versions_path.open("a") as f:
        f.write(log_line + "\n")


def print_status(root: Path) -> None:
    raw_root = root / "raw"
    if not raw_root.is_dir():
        print(f"no raw/ tree found under {root}")
        return
    for kind_dir in sorted(p for p in raw_root.iterdir() if p.is_dir()):
        kind = kind_dir.name
        gens = sorted(
            int(m.group(1))
            for m in (GEN_RE.match(p.name) for p in kind_dir.iterdir() if p.is_dir())
            if m
        )
        print(f"kind={kind}")
        for gen in gens:
            gen_tag = f"gen{gen}"
            schema_dir = root / "processed" / kind / gen_tag
            schemas = sorted(
                int(m.group(1))
                for m in (
                    SCHEMA_RE.match(p.name)
                    for p in (schema_dir.iterdir() if schema_dir.is_dir() else [])
                    if p.is_dir()
                )
                if m
            )
            schema_str = ", ".join(f"schema{s}" for s in schemas) or "(none)"
            print(f"  {gen_tag}: {schema_str}")


# ---------------------------------------------------------------------------
# update-manifest
# ---------------------------------------------------------------------------

def _find_schema_idx(abs_path: Path) -> int | None:
    """Return the index of the first schemaN component in abs_path.parts, or None."""
    for i, part in enumerate(abs_path.parts):
        if SCHEMA_RE.match(part):
            return i
    return None


def plan_update_manifest(
    manifest_path: Path, target_schema: str | None
) -> tuple[list[tuple[str, str | None]], list[Path]]:
    """Parse a manifest and plan schema replacements for each data line.

    Returns:
        lines: list of (original_line, new_relative_path_or_None)
            None means the line is unchanged (comment, blank, or already at target).
        missing: resolved absolute paths that don't exist on disk.
    """
    manifest_path = manifest_path.resolve()
    if not manifest_path.exists():
        raise SystemExit(f"error: manifest not found: {manifest_path}")
    manifest_dir = manifest_path.parent
    raw_lines = manifest_path.read_text().splitlines()

    result: list[tuple[str, str | None]] = []
    missing: list[Path] = []
    schema_cache: dict[Path, str] = {}

    for raw in raw_lines:
        stripped = raw.strip()
        if not stripped or stripped.startswith("#"):
            result.append((raw, None))
            continue

        old_abs = (manifest_dir / stripped).resolve()
        schema_idx = _find_schema_idx(old_abs)
        if schema_idx is None:
            result.append((raw, None))
            continue

        parts = list(old_abs.parts)
        old_schema = parts[schema_idx]
        gen_dir = Path(*parts[:schema_idx])

        if target_schema is not None:
            new_schema = target_schema
        else:
            if gen_dir not in schema_cache:
                n = _max_index(gen_dir, SCHEMA_RE)
                if n == 0:
                    raise SystemExit(f"error: no schema dirs found under {gen_dir}")
                schema_cache[gen_dir] = f"schema{n}"
            new_schema = schema_cache[gen_dir]

        if new_schema == old_schema:
            result.append((raw, None))
            continue

        parts[schema_idx] = new_schema
        new_abs = Path(*parts)
        if not new_abs.exists():
            missing.append(new_abs)

        new_rel = os.path.relpath(new_abs, start=manifest_dir)
        result.append((raw, new_rel))

    return result, missing


def apply_update_manifest(manifest_path: Path, lines: list[tuple[str, str | None]]) -> None:
    out = [replacement if replacement is not None else original for original, replacement in lines]
    manifest_path.write_text("\n".join(out) + "\n")


# ---------------------------------------------------------------------------
# create-manifest
# ---------------------------------------------------------------------------

def _resolve_manifest_files(manifest_path: Path) -> list[Path]:
    """Read a manifest and return its entries as resolved absolute paths."""
    files = []
    for line in manifest_path.read_text().splitlines():
        line = line.strip()
        if not line or line.startswith("#"):
            continue
        files.append((manifest_path.parent / line).resolve())
    return files


def plan_create_manifest(
    output_path: Path, parquet_files: list[Path]
) -> tuple[list[str], list[Path], list[Path]]:
    """Return (relative_lines, missing_files, resolved_abs_paths)."""
    manifest_dir = output_path.resolve().parent
    lines: list[str] = []
    missing: list[Path] = []
    resolved: list[Path] = []
    for p in parquet_files:
        abs_p = p.resolve()
        resolved.append(abs_p)
        if not abs_p.exists():
            missing.append(abs_p)
        lines.append(os.path.relpath(abs_p, start=manifest_dir))
    return lines, missing, resolved


def check_holdout_overlap(
    output_path: Path, resolved_new_files: list[Path]
) -> list[tuple[str, Path]]:
    """Return (other_manifest_name, file) pairs where new files clash with existing manifests.

    The check is triggered when output_path is (or will be) holdout.manifest, or when a
    holdout.manifest already exists in the same directory — in either case holdout data
    must be strictly isolated from all other pools.
    """
    output_resolved = output_path.resolve()
    manifest_dir = output_resolved.parent
    holdout_path = manifest_dir / "holdout.manifest"

    if output_resolved.name != "holdout.manifest" and not holdout_path.exists():
        return []

    new_set = set(resolved_new_files)
    overlaps: list[tuple[str, Path]] = []
    # When creating holdout, check against all other manifests (dev, full, …).
    # When creating dev/full, only check against holdout — dev vs full overlap is allowed.
    if output_resolved.name == "holdout.manifest":
        candidates = sorted(manifest_dir.glob("*.manifest"))
    else:
        candidates = [holdout_path]
    for existing in candidates:
        if existing.resolve() == output_resolved:
            continue
        try:
            existing_files = set(_resolve_manifest_files(existing))
        except OSError:
            continue
        for f in sorted(new_set & existing_files):
            overlaps.append((existing.name, f))
    return overlaps


def apply_create_manifest(output_path: Path, lines: list[str]) -> None:
    output_path.parent.mkdir(parents=True, exist_ok=True)
    output_path.write_text("\n".join(lines) + "\n")


# ---------------------------------------------------------------------------
# CLI
# ---------------------------------------------------------------------------

def main() -> None:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument(
        "--root",
        default="/ceph/lbogner/geant_steps",
        help="Dataset root for bump-gen/bump-schema/status (default: /ceph/lbogner/geant_steps)",
    )
    sub = parser.add_subparsers(dest="command", required=True)

    kind_help = "steps | hits | ... (default: steps)"

    p_gen = sub.add_parser("bump-gen", help="Cut a new raw generation")
    p_gen.add_argument("--kind", default="steps", help=kind_help)
    p_gen.add_argument("--reason", required=True, help="Why this gen exists")
    p_gen.add_argument("--by", default=None, help="Attribution (default: git user.name)")
    p_gen.add_argument("--date", default=None, help="Override date (default: today, ISO)")
    p_gen.add_argument("--execute", action="store_true", help="Apply (default: dry run)")

    p_schema = sub.add_parser("bump-schema", help="Cut a new schema within a gen")
    p_schema.add_argument("--kind", default="steps", help=kind_help)
    p_schema.add_argument("--gen", required=True, help="Existing gen tag, e.g. gen1")
    p_schema.add_argument("--reason", required=True, help="Why this schema exists")
    p_schema.add_argument("--by", default=None, help="Attribution (default: git user.name)")
    p_schema.add_argument("--date", default=None, help="Override date (default: today, ISO)")
    p_schema.add_argument("--execute", action="store_true", help="Apply (default: dry run)")

    p_update = sub.add_parser(
        "update-manifest",
        help="Repoint manifest(s) to a new schema, verifying all target files exist",
    )
    p_update.add_argument(
        "manifests", nargs="+", metavar="MANIFEST", help="One or more .manifest files to update"
    )
    p_update.add_argument(
        "--schema",
        default=None,
        metavar="schemaN",
        help="Target schema tag (default: highest schema found in the same gen dir)",
    )
    p_update.add_argument("--execute", action="store_true", help="Write updated manifests (default: dry run)")

    p_create = sub.add_parser(
        "create-manifest",
        help="Create a new manifest from a list of parquet files",
    )
    dest_group = p_create.add_mutually_exclusive_group(required=True)
    dest_group.add_argument(
        "--output", "-o", metavar="PATH", help="Explicit path for the new .manifest file"
    )
    dest_group.add_argument(
        "--pool", metavar="DETECTOR",
        help="Detector name; combined with --type and --root to form <root>/pools/<detector>/<type>.manifest",
    )
    p_create.add_argument(
        "--type", choices=["full", "holdout", "dev"],
        help="Pool type — full, holdout, or dev (required with --pool)",
    )
    p_create.add_argument(
        "files", nargs="+", metavar="FILE", help="Parquet files to include"
    )
    p_create.add_argument("--execute", action="store_true", help="Write the manifest (default: dry run)")

    sub.add_parser("status", help="List existing gens/schemas per kind")

    args = parser.parse_args()

    # Commands that need --root
    if args.command in ("bump-gen", "bump-schema", "status"):
        root = Path(args.root)
        if not root.is_dir():
            parser.error(f"{root} is not a directory")

    if args.command == "status":
        print_status(root)
        return

    if args.command in ("bump-gen", "bump-schema"):
        date = args.date or dt.date.today().isoformat()
        by = args.by if args.by is not None else _git_user_name()
        if args.command == "bump-gen":
            new_dirs, log_line = plan_bump_gen(root, args.kind, args.reason, by, date)
        else:
            new_dirs, log_line = plan_bump_schema(root, args.kind, args.gen, args.reason, by, date)

        print(f"=== {'EXECUTING' if args.execute else 'DRY RUN'} ===")
        print("new directories:")
        for d in new_dirs:
            print(f"  {d}")
        print("VERSIONS.md entry:")
        print(f"  {log_line}")

        if not args.execute:
            print("\nDry run only — pass --execute to apply.")
            return
        apply_bump(root, new_dirs, log_line)
        print("\nDone.")
        return

    if args.command == "update-manifest":
        if args.schema and not SCHEMA_RE.match(args.schema):
            parser.error(f"--schema must look like 'schemaN', got {args.schema!r}")

        all_plans: list[tuple[Path, list[tuple[str, str | None]]]] = []
        all_missing: list[Path] = []

        for raw in args.manifests:
            mp = Path(raw)
            plan, missing = plan_update_manifest(mp, args.schema)
            all_plans.append((mp.resolve(), plan))
            all_missing.extend(missing)

        print(f"=== {'EXECUTING' if args.execute else 'DRY RUN'} ===")
        for mp, plan in all_plans:
            changes = [(old, new) for old, new in plan if new is not None]
            print(f"\n{mp}  ({len(changes)} path(s) to update)")
            for old, new in changes:
                print(f"  - {old.strip()}")
                print(f"  + {new}")

        if all_missing:
            print(f"\nMISSING ({len(all_missing)} file(s) — target paths do not exist):")
            for p in all_missing:
                print(f"  {p}")
            if args.execute:
                raise SystemExit("error: refusing to write manifests with missing targets")

        if not args.execute:
            print("\nDry run only — pass --execute to apply.")
            return

        for mp, plan in all_plans:
            apply_update_manifest(mp, plan)
        print("\nDone.")
        return

    if args.command == "create-manifest":
        if args.pool is not None and args.type is None:
            parser.error("--type is required when --pool is given")

        if args.pool is not None:
            root = Path(args.root)
            output_path = root / "pools" / args.pool / f"{args.type}.manifest"
        else:
            output_path = Path(args.output)

        parquet_files = [Path(f) for f in args.files]
        lines, missing, resolved = plan_create_manifest(output_path, parquet_files)
        overlaps = check_holdout_overlap(output_path, resolved)

        print(f"=== {'EXECUTING' if args.execute else 'DRY RUN'} ===")
        print(f"manifest: {output_path.resolve()}")
        for line in lines:
            print(f"  {line}")

        if missing:
            print(f"\nMISSING ({len(missing)} file(s) do not exist):")
            for p in missing:
                print(f"  {p}")

        if overlaps:
            print(f"\nHOLDOUT OVERLAP ({len(overlaps)} file(s) appear in other manifests):")
            for name, f in overlaps:
                print(f"  {f}  (also in {name})")

        if (missing or overlaps) and args.execute:
            raise SystemExit("error: refusing to write manifest (see above)")

        if not args.execute:
            print("\nDry run only — pass --execute to apply.")
            return

        apply_create_manifest(output_path, lines)
        print("\nDone.")


if __name__ == "__main__":
    main()