"""Per-repo inventory: file trees, doc inventory, markers, git activity.

Writes tree_<repo>.txt, docs_inventory.tsv, markers.tsv, git_activity.tsv.
"""

import re
from collections import defaultdict
from datetime import date

from common import (
    DATA_DIR, DOC_SUFFIXES, assert_untouched, days_since, git, last_commit,
    ref_of, repos, tracked_files, write_tsv,
)

MARKER_RE = re.compile(r"\b(TODO|FIXME|HACK|XXX|DEPRECATED)\b")
# git grep's ERE does not implement \b, which silently reports zero
# markers; the scan therefore runs in Python, where \b works.

MAX_SCAN_BYTES = 512 * 1024


def write_trees():
    for name, repo in repos():
        files = tracked_files(name, repo)
        path = DATA_DIR / f"tree_{name}.txt"
        path.write_text("\n".join(files) + "\n", encoding="utf-8")
        print(f"  tree_{name}.txt: {len(files)} files")


def write_docs_inventory():
    rows = []
    for name, repo in repos():
        for f in tracked_files(name, repo):
            if not any(f.endswith(s) for s in DOC_SUFFIXES):
                continue
            size = (repo / f).stat().st_size
            iso, author, sha = last_commit(name, repo, f)
            rows.append([name, f, size, iso, author, days_since(iso), sha])
    rows.sort(key=lambda r: (r[0], r[1]))
    write_tsv(
        "docs_inventory.tsv",
        ["repo", "path", "bytes", "last_commit_date", "last_author",
         "days_since_change", "last_commit"],
        rows,
    )


def _blame_dates(repo, path, lines_wanted):
    """Map line number -> (author date, short sha, author) via one blame pass."""
    try:
        out = git(repo, "blame", "--line-porcelain", "--", path)
    except RuntimeError:
        return {}
    result, sha, author, when, lineno = {}, None, None, None, None
    for line in out.splitlines():
        if re.match(r"^[0-9a-f]{40} ", line):
            parts = line.split()
            sha, lineno = parts[0], int(parts[2])
        elif line.startswith("author "):
            author = line[len("author "):]
        elif line.startswith("author-time "):
            when = date.fromtimestamp(int(line[len("author-time "):])).isoformat()
        elif line.startswith("\t"):
            if lineno in lines_wanted:
                result[lineno] = (when or "", (sha or "")[:9], author or "")
    return result


def write_markers():
    rows = []
    for name, repo in repos():
        for f in tracked_files(name, repo):
            full = repo / f
            try:
                if full.stat().st_size > MAX_SCAN_BYTES:
                    continue
                text = full.read_text(encoding="utf-8")
            except (OSError, UnicodeDecodeError):
                continue  # binary or unreadable: not a marker carrier
            hits = {}
            for i, line in enumerate(text.splitlines(), start=1):
                m = MARKER_RE.search(line)
                if m:
                    hits[i] = (m.group(1), line.strip()[:200])
            if not hits:
                continue
            blame = _blame_dates(repo, f, set(hits))
            for lineno in sorted(hits):
                marker, snippet = hits[lineno]
                when, sha, author = blame.get(lineno, ("", "", ""))
                rows.append([name, f, lineno, marker, snippet, when,
                             days_since(when), sha, author])
    rows.sort(key=lambda r: (r[0], r[1], r[2]))
    write_tsv(
        "markers.tsv",
        ["repo", "path", "line", "marker", "text", "blame_date",
         "days_since_blame", "blame_commit", "blame_author"],
        rows,
    )


def _is_doc(path):
    return any(path.endswith(s) for s in DOC_SUFFIXES)


def write_git_activity():
    rows = []
    for name, repo in repos():
        log = git(repo, "log", "--format=%x01%H\t%ad", "--date=short",
                  "--name-only", ref_of(name))
        per_month = defaultdict(lambda: {"commits": 0, "docs": 0, "code": 0,
                                         "docs_only": 0})
        commit_days = []
        for chunk in log.split("\x01"):
            if not chunk.strip():
                continue
            head, _, body = chunk.partition("\n")
            sha, iso = head.split("\t")
            files = [ln for ln in body.splitlines() if ln.strip()]
            touched_docs = any(_is_doc(f) for f in files)
            touched_code = any(not _is_doc(f) for f in files)
            bucket = per_month[iso[:7]]
            bucket["commits"] += 1
            bucket["docs"] += 1 if touched_docs else 0
            bucket["code"] += 1 if touched_code else 0
            bucket["docs_only"] += 1 if touched_docs and not touched_code else 0
            commit_days.append(iso)

        for month in sorted(per_month):
            b = per_month[month]
            for metric in ("commits", "docs", "code", "docs_only"):
                key = {"docs": "commits_touching_docs",
                       "code": "commits_touching_code",
                       "docs_only": "commits_docs_only"}.get(metric, metric)
                rows.append([name, month, key, b[metric]])

        days = sorted({d for d in commit_days})
        totals = {
            "commits": len(commit_days),
            "commits_touching_docs": sum(b["docs"] for b in per_month.values()),
            "commits_touching_code": sum(b["code"] for b in per_month.values()),
            "commits_docs_only": sum(b["docs_only"] for b in per_month.values()),
            "active_days": len(days),
            "first_commit": days[0] if days else "",
            "last_commit": days[-1] if days else "",
            "days_since_last_commit": days_since(days[-1]) if days else "",
        }
        gap, gap_from, gap_to = 0, "", ""
        for a, b in zip(days, days[1:]):
            ya, ma, da = (int(x) for x in a.split("-"))
            yb, mb, db = (int(x) for x in b.split("-"))
            delta = (date(yb, mb, db) - date(ya, ma, da)).days
            if delta > gap:
                gap, gap_from, gap_to = delta, a, b
        totals["max_gap_days"] = gap
        totals["max_gap_from"] = gap_from
        totals["max_gap_to"] = gap_to
        for metric in sorted(totals):
            rows.append([name, "ALL", metric, totals[metric]])

    rows.sort(key=lambda r: (r[0], r[1], r[2]))
    write_tsv("git_activity.tsv", ["repo", "scope", "metric", "value"], rows)


if __name__ == "__main__":
    assert_untouched()
    DATA_DIR.mkdir(parents=True, exist_ok=True)
    write_trees()
    write_docs_inventory()
    write_markers()
    write_git_activity()