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

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m' # No Color

# Configuration
OWNER="doomemacs"
REPO="doomemacs"
FILE="home/roles/emacs/default.nix"
# Use current working directory as repo root (allows running from anywhere in the repo)
REPO_ROOT="${REPO_ROOT:-$(git rev-parse --show-toplevel 2>/dev/null || pwd)}"
TARGET_FILE="$REPO_ROOT/$FILE"

echo -e "${GREEN}Updating DoomEmacs to latest commit...${NC}"

# Check if file exists
if [[ ! -f "$TARGET_FILE" ]]; then
    echo -e "${RED}Error: $TARGET_FILE not found${NC}"
    exit 1
fi

# Get the default branch first
echo "Fetching repository information..."
DEFAULT_BRANCH=$(curl -s "https://api.github.com/repos/$OWNER/$REPO" | jq -r '.default_branch')

if [[ -z "$DEFAULT_BRANCH" ]] || [[ "$DEFAULT_BRANCH" == "null" ]]; then
    echo -e "${RED}Error: Failed to fetch default branch${NC}"
    exit 1
fi

# Get the latest commit SHA from GitHub
echo "Fetching latest commit SHA from $DEFAULT_BRANCH branch..."
LATEST_SHA=$(curl -s "https://api.github.com/repos/$OWNER/$REPO/commits/$DEFAULT_BRANCH" | jq -r '.sha')

if [[ -z "$LATEST_SHA" ]] || [[ "$LATEST_SHA" == "null" ]]; then
    echo -e "${RED}Error: Failed to fetch latest commit SHA${NC}"
    exit 1
fi

echo -e "Latest commit: ${YELLOW}$LATEST_SHA${NC}"

# Get current SHA from file
CURRENT_SHA=$(grep -oP 'rev = "\K[^"]+' "$TARGET_FILE")
echo -e "Current commit: ${YELLOW}$CURRENT_SHA${NC}"

if [[ "$CURRENT_SHA" == "$LATEST_SHA" ]]; then
    echo -e "${GREEN}Already up to date!${NC}"
    exit 0
fi

# Update the rev field
echo "Updating rev in $FILE..."
sed -i "s/rev = \".*\"/rev = \"$LATEST_SHA\"/" "$TARGET_FILE"

# Fetch the new sha256 hash using nix-prefetch
echo "Fetching new sha256 hash..."
NEW_SHA256=$(nix-prefetch-url --unpack "https://github.com/$OWNER/$REPO/archive/$LATEST_SHA.tar.gz" 2>/dev/null)

if [[ -z "$NEW_SHA256" ]]; then
    echo -e "${RED}Error: Failed to fetch sha256 hash${NC}"
    # Revert the rev change
    sed -i "s/rev = \".*\"/rev = \"$CURRENT_SHA\"/" "$TARGET_FILE"
    exit 1
fi

# Convert to SRI hash format
SRI_HASH=$(nix hash to-sri --type sha256 "$NEW_SHA256")
echo -e "New sha256: ${YELLOW}$SRI_HASH${NC}"

# Update the sha256 field
sed -i "s|sha256 = \".*\"|sha256 = \"$SRI_HASH\"|" "$TARGET_FILE"

echo -e "${GREEN}Successfully updated DoomEmacs!${NC}"
echo -e "  Old commit: ${YELLOW}$CURRENT_SHA${NC}"
echo -e "  New commit: ${YELLOW}$LATEST_SHA${NC}"
echo -e "  New sha256: ${YELLOW}$SRI_HASH${NC}"
echo ""
echo "You can now rebuild your system with the updated DoomEmacs."