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

usage() {
    echo "Usage: $0 VERSION" >&2
    exit 2
}

die() {
    echo "error: $*" >&2
    exit 1
}

[ "$#" -eq 1 ] || usage

VERSION="$1"

case "$VERSION" in
    v*)
        TAG="$VERSION"
        VERSION="${VERSION#v}"
        ;;
    *)
        TAG="v$VERSION"
        ;;
esac

echo "Preparing release $VERSION..."

# Validate version format.
case "$VERSION" in
    ''|*[!0-9.]*)
        die "invalid version: $VERSION"
        ;;
esac

# Make sure we're in a Git repository.
git rev-parse --git-dir >/dev/null 2>&1 ||
    die "not a Git repository"

# Make sure the working tree is clean.
if [ -n "$(git status --porcelain)" ]; then
    echo "error: working tree is not clean." >&2
    echo >&2
    git status --short >&2
    echo >&2
    echo "Please commit, stash, or discard these changes first." >&2
    exit 1
fi

# Make sure the tag doesn't already exist.
if git rev-parse "$TAG" >/dev/null 2>&1; then
    die "tag $TAG already exists"
fi

# Find the latest tag so the release notes can be written from the commits
# included since the previous release.
LAST_TAG=$(git describe --tags --abbrev=0 2>/dev/null) ||
    die "no previous tag found"

echo "Updating Cargo.toml to $VERSION..."
manifest_tmp="Cargo.toml.tmp.$$"
if ! awk -v version="$VERSION" '
    /^\[package\]$/ { in_package = 1; print; next }
    /^\[/ { in_package = 0 }
    in_package && /^version[[:space:]]*=/ {
        print "version = \"" version "\""
        found = 1
        next
    }
    { print }
    END { if (!found) exit 1 }
' Cargo.toml > "$manifest_tmp"; then
    rm -f "$manifest_tmp"
    die "could not find the package version in Cargo.toml"
fi
mv "$manifest_tmp" Cargo.toml
cargo update --workspace

echo
echo "Commits since $LAST_TAG:"
git log --oneline "$LAST_TAG..HEAD"
echo
echo "Edit CHANGELOG.md now, then return here to continue."
if ! [ -r /dev/tty ]; then
    die "cannot pause for changelog editing without a terminal"
fi
printf "Press Enter when the changelog is ready... " > /dev/tty
IFS= read -r _ < /dev/tty || true

echo
echo "Review the release changes:"
git diff -- Cargo.toml Cargo.lock CHANGELOG.md
echo
printf "Create the release commit? [y/N] " > /dev/tty
IFS= read -r CONFIRMATION < /dev/tty || CONFIRMATION=""
case "$CONFIRMATION" in
    y|Y|yes|YES|Yes) ;;
    *)
        echo "Release cancelled before creating the release commit."
        exit 1
        ;;
esac

echo "Creating release commit..."
git add Cargo.toml Cargo.lock CHANGELOG.md
git commit -m "chore(release): prepare $VERSION"

echo
echo "Release commit ready for review:"
git show --stat --oneline --decorate HEAD
echo
echo "Review CHANGELOG.md and the release commit before continuing."
if ! [ -r /dev/tty ]; then
    die "cannot prompt for release confirmation without a terminal"
fi
printf "Create tag $TAG and push the release? [y/N] " > /dev/tty
IFS= read -r CONFIRMATION < /dev/tty || CONFIRMATION=""
case "$CONFIRMATION" in
    y|Y|yes|YES|Yes) ;;
    *)
        echo "Release cancelled before tagging and pushing."
        exit 1
        ;;
esac

echo "Creating tag $TAG..."
git tag -a "$TAG" -m "Release $VERSION"

echo "Pushing release..."
git push origin HEAD
git push origin "$TAG"

echo
echo "Release $VERSION created successfully."