Add README, new_cycle, weekly_review, and update habits.sh

new_cycle

@@ -0,0 +1,163 @@
+#!/usr/bin/env python3
+import argparse
+import re
+from datetime import date, datetime, timedelta
+from pathlib import Path
+
+
+H1_RE = re.compile(r"^# (?!#)")
+CYCLE_RE = re.compile(
+    r"^# Cycle (\d+) \((\d{2}/\d{2}/\d{4}) - (\d{2}/\d{2}/\d{4})\)$"
+)
+
+
+def previous_sun_sat(today: date):
+    # End on the most recent Saturday.
+    days_since_saturday = (today.weekday() + 2) % 7
+    end = today - timedelta(days=days_since_saturday)
+    start = end - timedelta(days=6)
+    return start, end
+
+
+def fmt(d: date):
+    return d.strftime("%m/%d/%Y")
+
+
+def parse_date(s: str):
+    return datetime.strptime(s, "%m/%d/%Y").date()
+
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "file",
+        nargs="?",
+        default="~/.local/share/os/tasks.md",
+        help="Task markdown file (default: ~/.local/share/os/tasks.md)",
+    )
+    parser.add_argument("--today", help="Override today, format YYYY-MM-DD")
+    args = parser.parse_args()
+
+    path = Path(args.file).expanduser()
+    lines = path.read_text().splitlines(keepends=True)
+
+    today = (
+        datetime.strptime(args.today, "%Y-%m-%d").date()
+        if args.today
+        else date.today()
+    )
+
+    target_start, target_end = previous_sun_sat(today)
+
+    cycles = []
+    for line in lines:
+        m = CYCLE_RE.match(line.strip())
+        if m:
+            cycles.append((int(m.group(1)), parse_date(m.group(2)), parse_date(m.group(3))))
+
+    max_cycle = max((cycle[0] for cycle in cycles), default=0)
+    latest_end = max((cycle[2] for cycle in cycles), default=None)
+
+    if latest_end is not None and latest_end >= target_end:
+        print(f"Nothing to do; latest cycle already ends {fmt(latest_end)}")
+        return
+
+    missing_cycles = []
+    if latest_end is None:
+        missing_cycles.append((max_cycle + 1, target_start, target_end))
+    else:
+        cycle_start = latest_end + timedelta(days=1)
+        cycle_num = max_cycle + 1
+        while cycle_start + timedelta(days=6) <= target_end:
+            cycle_end = cycle_start + timedelta(days=6)
+            missing_cycles.append((cycle_num, cycle_start, cycle_end))
+            cycle_start += timedelta(days=7)
+            cycle_num += 1
+
+    if not missing_cycles:
+        print("Nothing to do")
+        return
+
+    current_start = None
+    for i, line in enumerate(lines):
+        if line.strip() == "# Current":
+            current_start = i
+            break
+
+    if current_start is None:
+        raise SystemExit("Could not find '# Current' section")
+
+    current_end = len(lines)
+    for i in range(current_start + 1, len(lines)):
+        if H1_RE.match(lines[i]):
+            current_end = i
+            break
+
+    done_header = None
+    for i in range(current_start + 1, current_end):
+        if lines[i].strip() == "## Done":
+            done_header = i
+            break
+
+    if done_header is None:
+        raise SystemExit("Could not find '## Done' under '# Current'")
+
+    done_start = done_header + 1
+    done_end = current_end
+    for i in range(done_start, current_end):
+        if lines[i].startswith("## "):
+            done_end = i
+            break
+
+    done_lines = lines[done_start:done_end]
+
+    while done_lines and not done_lines[0].strip():
+        done_lines.pop(0)
+    while done_lines and not done_lines[-1].strip():
+        done_lines.pop()
+
+    # Empty Current -> Done section. If there are no done items, still create
+    # the new cycle block with an empty Done section.
+    lines = lines[:done_start] + ["\n"] + lines[done_end:]
+
+    # Re-find end of Current after edit.
+    current_start = next(i for i, line in enumerate(lines) if line.strip() == "# Current")
+    insert_at = len(lines)
+    for i in range(current_start + 1, len(lines)):
+        if H1_RE.match(lines[i]):
+            insert_at = i
+            break
+
+    cycle_block = []
+    latest_cycle = missing_cycles[-1]
+    for cycle_num, cycle_start, cycle_end in reversed(missing_cycles):
+        cycle_block.extend([
+            f"# Cycle {cycle_num} ({fmt(cycle_start)} - {fmt(cycle_end)})\n",
+            "\n",
+        ])
+        if (cycle_num, cycle_start, cycle_end) == latest_cycle:
+            cycle_block.extend(done_lines)
+        cycle_block.append("\n")
+
+    prefix = lines[:insert_at]
+    suffix = lines[insert_at:]
+
+    if prefix and prefix[-1].strip():
+        prefix.append("\n")
+
+    if suffix and suffix[0].strip():
+        cycle_block.append("\n")
+
+    path.write_text("".join(prefix + cycle_block + suffix))
+
+    if len(missing_cycles) == 1:
+        cycle_num, cycle_start, cycle_end = missing_cycles[0]
+        print(f"Created # Cycle {cycle_num} ({fmt(cycle_start)} - {fmt(cycle_end)})")
+    else:
+        first_num = missing_cycles[0][0]
+        last_num = missing_cycles[-1][0]
+        print(f"Created cycles {first_num}-{last_num}")
+
+
+if __name__ == "__main__":
+    main()