#!/usr/bin/env bash
set -euo pipefail

# Compute next CalVer version: YYYY.MM.BUILD
# Uses git tags to find the latest release, increments build number.
# Resets build to 1 on new month or if no prior release exists.

YEAR_MONTH=$(date +"%Y.%-m")

# Get latest version tag (CalVer format: YYYY.M.BUILD)
LATEST=$(git tag -l '[0-9]*.[0-9]*.[0-9]*' --sort=-v:refname | head -1 || true)

if [ -z "$LATEST" ]; then
    echo "${YEAR_MONTH}.1"
    exit 0
fi

# Parse existing tag
LATEST_YM=$(echo "$LATEST" | sed 's/\.[^.]*$//')
LATEST_BUILD=$(echo "$LATEST" | grep -o '[^.]*$')

if [ "$LATEST_YM" = "$YEAR_MONTH" ]; then
    echo "${YEAR_MONTH}.$((LATEST_BUILD + 1))"
else
    echo "${YEAR_MONTH}.1"
fi