#!/usr/bin/env nix-shell
#!nix-shell --pure -i bash -p bash curl nix nix-prefetch cacert git
set -euo pipefail

# Update msty-studio AppImage hash.
#
# Upstream publishes to an unversioned URL (MstyStudio_x86_64.AppImage) — no
# version-pinned URL and no usable GitHub release. To still catch updates, we:
#   1. HEAD the URL and read the Last-Modified header
#   2. Compare to the value stored as a `# last-modified:` comment in default.nix
#   3. If changed: re-download, compute sha256, update hash + comment, commit
#
# The version attribute stays static (manual bump) — only the binary hash is
# refreshed automatically.

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
NIX_FILE="$SCRIPT_DIR/default.nix"
URL="https://next-assets.msty.studio/app/alpha/linux/MstyStudio_x86_64.AppImage"

echo "Checking $URL ..."
HEADERS=$(curl -fsSIL "$URL")
NEW_LAST_MODIFIED=$(echo "$HEADERS" | tr -d '\r' \
  | awk -F': ' 'tolower($1)=="last-modified" {print $2; exit}')

if [[ -z "$NEW_LAST_MODIFIED" ]]; then
  echo "ERROR: Could not read Last-Modified header from $URL" >&2
  exit 1
fi

CURRENT_LAST_MODIFIED=$(awk -F': ' '/^# last-modified:/ {sub(/^# last-modified: /, ""); print; exit}' "$NIX_FILE")

echo "Current: ${CURRENT_LAST_MODIFIED:-<none>}"
echo "Latest:  $NEW_LAST_MODIFIED"

if [[ "$NEW_LAST_MODIFIED" == "$CURRENT_LAST_MODIFIED" ]]; then
  echo "No change, nothing to do."
  exit 0
fi

echo "==> Content changed, refreshing hash..."

HASH=$(nix-prefetch-url --type sha256 "$URL" 2>/dev/null)
SRI=$(nix hash convert --hash-algo sha256 --to sri "$HASH")
echo "New sha256: $SRI"

sed -i "s|^\([[:space:]]*\)sha256 = \"[^\"]*\";|\1sha256 = \"$SRI\";|" "$NIX_FILE"

if grep -q '^# last-modified:' "$NIX_FILE"; then
  sed -i "s|^# last-modified:.*|# last-modified: $NEW_LAST_MODIFIED|" "$NIX_FILE"
else
  sed -i "1i # last-modified: $NEW_LAST_MODIFIED" "$NIX_FILE"
fi

echo "Updated $NIX_FILE"

NIXPKGS_ROOT=$(git -C "$SCRIPT_DIR" rev-parse --show-toplevel 2>/dev/null || true)
if [[ -n "$NIXPKGS_ROOT" ]] && \
   [[ -n "$(git -C "$NIXPKGS_ROOT" status --porcelain "$NIX_FILE")" ]]; then
  git -C "$NIXPKGS_ROOT" add "$NIX_FILE"
  git -C "$NIXPKGS_ROOT" commit -m "msty-studio: refresh AppImage ($NEW_LAST_MODIFIED)"
  echo "==> Committed"
fi