#!/usr/bin/env python3
"""Report git insertions for a calendar day, by hour × language (file extension).

Default: today's commits in the current repo (AuthorDate, local clock).
Skips binary numstat rows (added/deleted marked '-').
"""

from __future__ import annotations

import argparse
import collections
import os
import subprocess
import sys
from datetime import date, datetime, timedelta
from pathlib import Path

LANG = {
    ".c": "C",
    ".h": "C",
    ".cc": "C++",
    ".cpp": "C++",
    ".hpp": "C++",
    ".md": "Markdown",
    ".sh": "Shell",
    ".py": "Python",
    ".gd": "GDScript",
    ".json": "JSON",
    ".txt": "Text",
    ".toml": "TOML",
    ".yml": "YAML",
    ".yaml": "YAML",
    ".cmake": "CMake",
    ".png": "PNG (bin)",
    ".jpg": "JPEG (bin)",
    ".jpeg": "JPEG (bin)",
}


def lang_of(path: str) -> str:
    ext = Path(path).suffix.lower()
    if ext in LANG:
        return LANG[ext]
    if ext:
        return ext[1:].upper()
    return "noext"


def day_bounds(day: date) -> tuple[str, str]:
    start = datetime(day.year, day.month, day.day, 0, 0, 0)
    end = start + timedelta(days=1)
    fmt = "%Y-%m-%d %H:%M:%S"
    return start.strftime(fmt), end.strftime(fmt)


def load_numstat(repo: Path, since: str, until: str) -> str:
    return subprocess.check_output(
        [
            "git",
            "-C",
            str(repo),
            "log",
            f"--since={since}",
            f"--until={until}",
            "--pretty=format:COMMIT\t%ad\t%H\t%s",
            "--date=format:%Y-%m-%d %H:%M:%S",
            "--numstat",
        ],
        text=True,
    )


def aggregate(out: str) -> tuple[
    dict[str, dict[str, int]],
    dict[str, int],
    dict[str, int],
    dict[str, list[int]],
    int,
    int,
]:
    by_hour_lang: dict[str, dict[str, int]] = collections.defaultdict(
        lambda: collections.defaultdict(int)
    )
    by_lang: dict[str, int] = collections.defaultdict(int)
    by_hour: dict[str, int] = collections.defaultdict(int)
    net: dict[str, list[int]] = collections.defaultdict(lambda: [0, 0])
    commits = 0
    binary_skips = 0
    cur_hour: str | None = None

    for line in out.splitlines():
        if not line.strip():
            continue
        if line.startswith("COMMIT\t"):
            _, ad, _h, _s = line.split("\t", 3)
            dt = datetime.strptime(ad, "%Y-%m-%d %H:%M:%S")
            cur_hour = dt.strftime("%H:00")
            commits += 1
            continue
        parts = line.split("\t")
        if len(parts) != 3 or cur_hour is None:
            continue
        added_s, deleted_s, path = parts
        if added_s == "-" or deleted_s == "-":
            binary_skips += 1
            continue
        added = int(added_s)
        deleted = int(deleted_s)
        lang = lang_of(path)
        by_hour_lang[cur_hour][lang] += added
        by_lang[lang] += added
        by_hour[cur_hour] += added
        net[lang][0] += added
        net[lang][1] += deleted

    return by_hour_lang, by_lang, by_hour, net, commits, binary_skips


def print_report(
    repo: Path,
    day: date,
    by_hour_lang: dict[str, dict[str, int]],
    by_lang: dict[str, int],
    by_hour: dict[str, int],
    net: dict[str, list[int]],
    commits: int,
    binary_skips: int,
) -> None:
    hours = sorted(by_hour.keys())
    langs = sorted(by_lang.keys(), key=lambda x: (-by_lang[x], x))
    print(f"REPO={repo}")
    print(f"DAY={day.isoformat()}  COMMITS={commits}  BINARY_FILE_TOUCHES_SKIPPED={binary_skips}")
    print()
    print("=== +Zeilen je Stunde × Sprache (nur Insertions, nicht Netto) ===")
    if not hours:
        print("(keine Commits an diesem Tag)")
        return
    print(f"{'Stunde':<8}" + "".join(f"{l:>12}" for l in langs) + f"{'TOTAL':>12}")
    for h in hours:
        row = f"{h:<8}"
        for l in langs:
            v = by_hour_lang[h].get(l, 0)
            row += f"{v:>12}" if v else f"{'·':>12}"
        row += f"{by_hour[h]:>12}"
        print(row)
    print(
        f"{'SUMME':<8}"
        + "".join(f"{by_lang[l]:>12}" for l in langs)
        + f"{sum(by_lang.values()):>12}"
    )
    print()
    print("=== Tages-Total nach Sprache ===")
    for l in langs:
        print(f"  {l:<12} +{by_lang[l]:,}")
    print(f"  {'TOTAL':<12} +{sum(by_lang.values()):,}")
    print()
    print("=== Netto (+/−) (Kurz) ===")
    for l in langs:
        a, d = net[l]
        print(f"  {l:<12} +{a:,}  −{d:,}  net {a - d:+,}")
    total_a = sum(v[0] for v in net.values())
    total_d = sum(v[1] for v in net.values())
    print(f"  {'TOTAL':<12} +{total_a:,}  −{total_d:,}  net {total_a - total_d:+,}")


def parse_day(s: str) -> date:
    return date.fromisoformat(s)


def main() -> int:
    ap = argparse.ArgumentParser(
        description="Git insertions for one calendar day, by hour × language."
    )
    ap.add_argument(
        "--repo",
        type=Path,
        default=Path("."),
        help="git repo root (default: cwd)",
    )
    ap.add_argument(
        "--day",
        type=parse_day,
        default=date.today(),
        help="calendar day YYYY-MM-DD (default: today)",
    )
    args = ap.parse_args()
    repo = args.repo.resolve()
    if not (repo / ".git").exists() and not (repo / ".git").is_file():
        # worktree .git may be a file; also accept git rev-parse
        try:
            top = subprocess.check_output(
                ["git", "-C", str(repo), "rev-parse", "--show-toplevel"],
                text=True,
            ).strip()
            repo = Path(top)
        except subprocess.CalledProcessError:
            print(f"ERROR: not a git repo: {repo}", file=sys.stderr)
            return 2

    since, until = day_bounds(args.day)
    out = load_numstat(repo, since, until)
    by_hour_lang, by_lang, by_hour, net, commits, binary_skips = aggregate(out)
    print_report(
        repo, args.day, by_hour_lang, by_lang, by_hour, net, commits, binary_skips
    )
    return 0


if __name__ == "__main__":
    raise SystemExit(main())