#!/usr/bin/env python3
"""Generate compound tasks by combining already-validated single defects.

Every single-defect task in the corpus has been through the builder, so its
fault is known findable and its tests known correct against the reference. A
compound is the union of several such tasks whose broken files are disjoint --
that disjointness is what guarantees no single edit repairs more than one, which
is the property the difficulty dial depends on.

Nothing is invented here: the break overlays and the tests are the ones already
validated, and only the instruction is composed.
"""
import argparse, itertools, json, sys
from pathlib import Path

sys.path.insert(0, str(Path(__file__).parent))
from make_tasks import CORPUS  # noqa: E402


def read_tree(root: Path) -> dict:
    if not root.is_dir():
        return {}
    return {str(p.relative_to(root)): p.read_text()
            for p in sorted(root.rglob("*")) if p.is_file()}


def load_singles(repo: str):
    """Every task in `repo` that breaks exactly one file and is not compound."""
    out = []
    tasks_dir = CORPUS / repo / "tasks"
    for task_dir in sorted(tasks_dir.glob("*")):
        meta_path = task_dir / "task.json"
        if not meta_path.is_file():
            continue
        meta = json.loads(meta_path.read_text())
        if meta.get("compound"):
            continue
        broken = read_tree(task_dir / "break")
        tests = read_tree(task_dir / "tests")
        if len(broken) != 1 or not tests:
            continue          # compounds and malformed tasks are not ingredients
        out.append({
            "id": task_dir.name,
            "files": broken,
            "tests": tests,
            "instruction": meta["instruction"],
            "difficulty": meta.get("difficulty", 3),
        })
    return out


def compose_instruction(parts) -> str:
    """One triage ticket listing each symptom, renumbered."""
    head = (f"{len(parts)} findings from this week's triage. They have separate "
            f"causes and are not related to one another; all {len(parts)} need "
            f"fixing.\n")
    body = []
    for n, part in enumerate(parts, 1):
        # keep only the symptom prose, dropping each source task's own numbering
        text = part["instruction"].strip()
        text = "\n   ".join(line.strip() for line in text.splitlines() if line.strip())
        body.append(f"\n{n}. {text}")
    return head + "\n".join(body)


def build(repo: str, lang: str, size: int, limit: int, prefix: str):
    singles = load_singles(repo)
    made, used_pairs = 0, set()
    # Cap how often one defect is reused. Without this the generator anchors
    # nearly every compound on whichever ingredient sorts first, which
    # correlates the outcomes: one defect a model cannot fix would sink most of
    # the corpus at once, and the resolved rate would measure that single bug
    # rather than the breadth it is meant to.
    max_uses = max(2, (limit * size) // max(len(singles), 1) + 1)
    uses: dict = {}

    for combo in itertools.combinations(singles, size):
        if made >= limit:
            break
        touched = [set(c["files"]) for c in combo]
        # disjoint files: no single edit can repair two of them
        if any(a & b for a, b in itertools.combinations(touched, 2)):
            continue
        ids = tuple(sorted(c["id"] for c in combo))
        if any(uses.get(i, 0) >= max_uses for i in ids):
            continue
        # avoid re-using the same pair of ingredients across many compounds
        pairs = set(itertools.combinations(ids, 2))
        if pairs & used_pairs:
            continue
        used_pairs |= pairs
        for i in ids:
            uses[i] = uses.get(i, 0) + 1

        merged_files, merged_tests = {}, {}
        for part in combo:
            merged_files.update(part["files"])
            for name, body in part["tests"].items():
                key = name
                if key in merged_tests and merged_tests[key] != body:
                    stem, dot, ext = name.partition(".")
                    key = f"{stem}_{part['id'].replace('-', '_')}{dot}{ext}"
                merged_tests[key] = body

        task_id = f"{prefix}-{made + 1:02d}"
        tdir = CORPUS / repo / "tasks" / task_id
        (tdir / "tests").mkdir(parents=True, exist_ok=True)
        for rel, content in merged_files.items():
            out = tdir / "break" / rel
            out.parent.mkdir(parents=True, exist_ok=True)
            out.write_text(content)
        for name, body in merged_tests.items():
            (tdir / "tests" / name).write_text(body)
        (tdir / "task.json").write_text(json.dumps({
            "lang": lang,
            "category": "logic",
            "difficulty": 5,
            "compound": True,
            "ingredients": list(ids),
            "instruction": compose_instruction(combo),
        }, indent=2) + "\n")
        print(f"  {task_id}: {' + '.join(ids)}")
        made += 1

    print(f"{made} compound task(s) for {repo}")
    return made


if __name__ == "__main__":
    ap = argparse.ArgumentParser()
    ap.add_argument("--size", type=int, default=3, help="defects per compound")
    ap.add_argument("--limit", type=int, default=8, help="max compounds per repo")
    args = ap.parse_args()

    total = 0
    for repo, lang, prefix in (("python/scheduler", "python", "triage"),
                               ("typescript/router", "typescript", "review"),
                               ("python/ledger", "python", "audit")):
        total += build(repo, lang, args.size, args.limit, f"{prefix}{args.size}")
    print(f"\n{total} total")