#!/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)
# Entries prefixed with ? are sample files -- we don't remove those on upgrade.
old_files=()
old_samples=()
while IFS= read -r line; do
    [[ "$line" =~ ^[[:space:]]*# ]] && continue
    [[ -z "$line" ]] && continue
    if [[ "$line" == \?* ]]; then
        old_samples+=("${line#\?}")
    else
        old_files+=("$line")
    fi
done < "$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=()
new_samples=()
while IFS= read -r line; do
    [[ "$line" =~ ^[[:space:]]*# ]] && continue
    [[ -z "$line" ]] && continue
    if [[ "$line" == \?* ]]; then
        new_samples+=("${line#\?}")
    else
        new_files+=("$line")
    fi
done < "$tmpdir/diachron/file-list"

# Remove old framework files (not samples -- those belong to the user)
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

# Handle sample files: copy only if the user doesn't already have them
samples_added=()
samples_skipped=()
for f in "${new_samples[@]}"; do
    if [ -e "$DIR/$f" ]; then
        samples_skipped+=("$f")
    else
        # New sample that doesn't exist yet -- copy it in
        (cd "$tmpdir/diachron" && tar cf - "$f") | (cd "$DIR" && tar xf -)
        git -C "$DIR" add "$f"
        samples_added+=("$f")
    fi
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."

if [ ${#samples_added[@]} -gt 0 ]; then
    echo ""
    echo "New sample files added:"
    for f in "${samples_added[@]}"; do
        echo "  + $f"
    done
fi

if [ ${#samples_skipped[@]} -gt 0 ]; then
    echo ""
    echo "Sample files skipped (you already have these):"
    for f in "${samples_skipped[@]}"; do
        echo "  ~ $f"
    done
fi

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"