#!/bin/bash

set -eu
set -o pipefail
IFS=$'\n\t'

DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

new_ref="${1:?Usage: upgrade.sh <new-ref>}"

cached_repo="$HOME/.cache/diachron/v1/repositories/diachron.git"
tmpdir=""

cleanup() {
    if [ -n "$tmpdir" ]; then
        rm -rf "$tmpdir"
    fi
}
trap cleanup EXIT

echo "=== Diachron Framework Upgrade ==="
echo ""
echo "This will replace all framework files in your project."
echo "Make sure you have committed or backed up any local changes."
echo ""
read -r -p "Continue? [y/N] " answer
if [[ ! "$answer" =~ ^[Yy]$ ]]; then
    echo "Aborted."
    exit 0
fi

# Update cached repository
"$DIR/update-cached-repository.sh"

# Read current version
if [ ! -f "$DIR/.diachron-version" ]; then
    echo "Error: .diachron-version not found." >&2
    echo "Is this a diachron project?" >&2
    exit 1
fi
old_ref=$(cat "$DIR/.diachron-version")

# Verify both refs exist in cached repo
if ! git -C "$cached_repo" rev-parse --verify "$old_ref^{commit}" >/dev/null 2>&1; then
    echo "Error: current version '$old_ref' not found in cached repository." >&2
    exit 1
fi
if ! git -C "$cached_repo" rev-parse --verify "$new_ref^{commit}" >/dev/null 2>&1; then
    echo "Error: target version '$new_ref' not found in cached repository." >&2
    exit 1
fi

# Require a clean working tree
if [ -n "$(git -C "$DIR" status --porcelain)" ]; then
    echo "Error: working tree is not clean." >&2
    echo "Commit or stash all changes (including untracked files) before upgrading." >&2
    exit 1
fi

echo ""
echo "Upgrading: $old_ref -> $new_ref"
echo ""

# Read current file-list (files to remove)
old_files=()
while IFS= read -r line; do
    [[ "$line" =~ ^[[:space:]]*# ]] && continue
    [[ -z "$line" ]] && continue
    old_files+=("$line")
done < "$DIR/file-list"

# Clone and checkout new version into a temp directory
tmpdir=$(mktemp -d)
git clone --quiet "$cached_repo" "$tmpdir/diachron"
git -C "$tmpdir/diachron" checkout --quiet "$new_ref"

# Read new file-list (files to add)
new_files=()
while IFS= read -r line; do
    [[ "$line" =~ ^[[:space:]]*# ]] && continue
    [[ -z "$line" ]] && continue
    new_files+=("$line")
done < "$tmpdir/diachron/file-list"

# Remove old framework files
for f in "${old_files[@]}"; do
    git -C "$DIR" rm -rf --quiet --ignore-unmatch "$f"
done

# Copy in new framework files
(cd "$tmpdir/diachron" && tar cf - "${new_files[@]}") | (cd "$DIR" && tar xf -)

# Stage them
for f in "${new_files[@]}"; do
    git -C "$DIR" add "$f"
done

# Update version marker
echo "$new_ref" > "$DIR/.diachron-version"
git -C "$DIR" add "$DIR/.diachron-version"

echo "=== Upgrade staged: $old_ref -> $new_ref ==="
echo ""
echo "Framework files have been removed, replaced, and staged."
echo ""
echo "Next steps:"
echo "  1. Review:   git diff --cached"
echo "  2. Commit:   git commit -m 'Upgrade diachron to $new_ref'"
echo "  3. Install:  ./sync.sh"