#!/usr/bin/env python3
"""
issue_index.py — rebuild tmp/issues/INDEX.md from what is on disk. Offline.

A map of the local store, nothing else. The `origin` column is the only place
the index acknowledges that a tracker exists: `local` means the issue has never
left this machine, `gitea` means the sync layer has pushed or pulled it. Both
are ordinary issues here.

The store is <repo root>/tmp/issues unless --out says otherwise; an existing
store with nothing in it gets an "_empty_" table, a store that is not there is
an error rather than a directory to create.

Usage:
    issue_index.py [--out DIR]
"""
import argparse
import os
import re
import sys

sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
import issue  # noqa: E402


def cell(v):
    if isinstance(v, (list, tuple)):
        return ", ".join(str(x) for x in v) or "—"
    v = str(v or "").strip()
    return v.replace("|", "\\|") or "—"


def progress(body):
    """`3/7` for a body with checkboxes, "" for one without.

    Counted from the body every time the index is built and stored nowhere —
    the boxes are the state, and a second copy of it in a metadata field would
    be wrong by the next edit."""
    done, total = issue.checkbox_progress(body)
    return "%d/%d" % (done, total) if total else ""


def build(root):
    # An index of a store that is not there is not an empty index, it is a bad
    # path. Raising beats writing INDEX.md into a directory nobody asked for.
    issue.require_store(root)
    issues = issue.load_all(root)
    rows = []
    for i in sorted(issues):
        iss = issues[i]
        rest = [l for l in iss.labels if not l.startswith("type/")]
        rows.append({
            "id": i,
            "state": cell(iss.state),
            "progress": progress(iss.body),
            "type": cell(iss.type),
            "labels": cell(rest),
            "title": cell(iss.title),
            "milestone": cell(iss.milestone),
            "depends": cell(iss.depends),
            "origin": cell(iss.origin),
        })

    listing = os.listdir(root) if os.path.isdir(root) else []
    trees = sorted(f for f in listing if re.match(r'^tree-.+\.md$', f))

    out = ["# Issue store", "",
           "Every issue this project knows about. `origin: local` means it "
           "exists nowhere else — a complete state, not a pending one. Any "
           "other value names the tracker it also lives in; the handle is in "
           "the file. `progress` counts the body's checkboxes, ticked over "
           "total, and is blank for an issue that has none — read off the "
           "body at build time, stored nowhere. Rebuild with `issue_index.py`; "
           "tick a box with `issue_ac.py`.", ""]
    if rows:
        out += ["| id | state | progress | type | labels | title | milestone | depends | origin |",
                "|---|---|---|---|---|---|---|---|---|"]
        out += ["| [%s](%s.md) | %s | %s | %s | %s | %s | %s | %s | %s |" % (
            r["id"], r["id"], r["state"], r["progress"], r["type"], r["labels"],
            r["title"], r["milestone"], r["depends"], r["origin"]) for r in rows]
    else:
        out.append("_empty_")

    if trees:
        out += ["", "## Dependency trees", ""]
        out += ["- [%s](%s)" % (t, t) for t in trees]

    cycles = issue.find_cycles(issue.graph(issues))
    if cycles:
        out += ["", "## Dependency cycles", ""]
        out += ["- %s" % " -> ".join(c) for c in cycles]

    out.append("")
    path = os.path.join(root, "INDEX.md")
    with open(path, "w") as f:
        f.write("\n".join(out))
    return path, len(rows)


def main():
    ap = argparse.ArgumentParser(description="Rebuild the local issue index (offline)")
    ap.add_argument("--out", default=issue.ISSUE_ROOT,
                    help="store root (default: <repo>/tmp/issues)")
    args = ap.parse_args()
    # An existing store with nothing in it is a legitimate thing to index — it
    # gets an "_empty_" table. A store that is not there is not.
    try:
        path, n = build(args.out)
    except issue.StoreMissing as e:
        sys.exit("issue_index.py: %s — nothing was created; create an issue with "
                 "issue_new.py, or pass --out" % e)
    print("%s — %d issue(s)" % (path, n))


if __name__ == "__main__":
    main()