#!/usr/bin/env python3
"""Phase 0 gate — deterministic pre-flight, NO model, NO parser logic.

Reproduces the Build-Plan Phase 0 gate (docs/BUILD-PLAN.md):
  - the fixture's line count must be 1316
  - print the distinct top-level `type` counts
And confirms the Phase-0 capability check: we can enumerate ~/.claude/projects
and read a .jsonl (TRACE-CONTRACT §1).

This is a pre-flight only. Turn/token/provenance numbers belong to Phase 1+.
Run:  python3 tools/phase0_check.py
"""
from __future__ import annotations
import json
import sys
from collections import Counter
from pathlib import Path

REPO = Path(__file__).resolve().parent.parent
FIXTURE = REPO / "fixtures" / "sample-session.jsonl"
EXPECTED_LINES = 1316  # TRACE-CONTRACT §6 — ground truth


def type_counts(path: Path) -> tuple[int, int, Counter]:
    """Return (parsed_lines, parse_failures, Counter of top-level `type`)."""
    counts: Counter = Counter()
    parsed = 0
    failures = 0
    with path.open(encoding="utf-8") as fh:
        for line in fh:
            line = line.strip()
            if not line:
                continue
            parsed += 1
            try:
                obj = json.loads(line)
            except json.JSONDecodeError:
                failures += 1
                continue
            counts[obj.get("type", "<none>")] += 1
    return parsed, failures, counts


def enumerate_projects() -> tuple[int, int]:
    """Phase-0 capability check: can we walk ~/.claude/projects and see sessions?"""
    root = Path.home() / ".claude" / "projects"
    if not root.is_dir():
        return 0, 0
    dirs = [p for p in root.iterdir() if p.is_dir()]
    sessions = list(root.glob("**/*.jsonl"))
    return len(dirs), len(sessions)


def main() -> int:
    if not FIXTURE.exists():
        print(f"FAIL — fixture missing: {FIXTURE}")
        return 1

    parsed, failures, counts = type_counts(FIXTURE)

    print("Her · हेर — Phase 0 pre-flight")
    print("=" * 52)
    print(f"fixture          : {FIXTURE}")
    print(f"line count       : {parsed}   (expected {EXPECTED_LINES})")
    print(f"json parse errors: {failures}")
    print("-" * 52)
    print("top-level `type` counts:")
    width = max(len(k) for k in counts) if counts else 0
    for name, n in sorted(counts.items(), key=lambda kv: (-kv[1], kv[0])):
        print(f"  {name:<{width}}  {n}")
    print(f"  {'TOTAL':<{width}}  {sum(counts.values())}")
    print("-" * 52)

    n_dirs, n_sessions = enumerate_projects()
    print(f"~/.claude/projects: {n_dirs} project dirs, {n_sessions} sessions readable")
    print("=" * 52)

    ok = (parsed == EXPECTED_LINES) and (failures == 0)
    print("GATE:", "PASS ✓" if ok else "FAIL ✗")
    return 0 if ok else 1


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