#!/bin/bash
set -e

# --- CONFIGURATION (Modify these for other projects/配置项) ---
# 1. The Git URL of the official upstream repository (上游官方仓库地址)
UPSTREAM_URL="https://github.com/TencentCloud/chat-uikit-flutter.git"

# 2. List of local directories/files to PROTECT from upstream changes (space separated)
#    e.g. "images/ assets/custom_config.json" (需要保护的本地目录或文件，空格分隔)
PROTECTED_PATHS="images/"
# -------------------------------------------------------

# Colors for output
GREEN='\033[0;32m'
BLUE='\033[0;34m'
RED='\033[0;31m'
NC='\033[0m' # No Color

echo -e "${BLUE}=== Starting Upstream Synchronization ===${NC}"

# 1. Verify we are in the root of the repo
for path in $PROTECTED_PATHS; do
    if [ ! -e "$path" ]; then
        echo -e "${RED}Warning: Protected path '$path' not found in current directory.${NC}"
    fi
done

# 2. Add upstream remote if not exists
if ! git remote | grep -q "upstream"; then
    echo "Adding upstream remote..."
    git remote add upstream "$UPSTREAM_URL"
fi

# 2.1 Stash local changes to prevent data loss during branch switching
echo -e "${BLUE}Stashing local changes...${NC}"
STASH_NEEDED=false
if ! git diff-index --quiet HEAD --; then
    git stash push -m "Stash before upstream sync"
    STASH_NEEDED=true
fi


# 3. Fetch upstream
echo -e "${BLUE}Fetching latest upstream changes...${NC}"
git fetch upstream

# 4. Update upstream-main branch (The Reference Branch)
echo -e "${BLUE}Updating upstream-main branch...${NC}"
if git show-ref --verify --quiet refs/heads/upstream-main; then
    git checkout upstream-main
    git reset --hard upstream/main
else
    git checkout -b upstream-main upstream/main
fi

# 5. Switch back to master
echo -e "${BLUE}Switching to master...${NC}"
git checkout master

# 5.1 Save the current master commit BEFORE merge (Critical Fix)
MASTER_BEFORE_MERGE=$(git rev-parse HEAD)

# 6. Merge upstream-main into master
echo -e "${BLUE}Merging upstream changes into master...${NC}"
# We use --no-commit to allow us to check/restore images before finalizing
if git merge --no-commit upstream-main; then
    echo "Merge prepared successfully."
else
    echo -e "${RED}Merge conflict detected.${NC}"
    echo "Attempting to auto-resolve protected paths conflicts by keeping OURS..."
    # If conflict is in protected paths, we force checkout master's version (before merge)
    for path in $PROTECTED_PATHS; do
        git checkout "$MASTER_BEFORE_MERGE" -- "$path" || true
    done
    echo "Note: Manual resolution may still be required for non-protected files."
fi

# 7. FORCE RESTORE PROTECTED PATHS (The Core Protection)
# Regardless of merge status, we ensure protected folders are exactly what we had before
echo -e "${BLUE}Ensuring protected paths are preserved...${NC}"
for path in $PROTECTED_PATHS; do
    git checkout "$MASTER_BEFORE_MERGE" -- "$path"
done

# 8. Check for conflicts
if git ls-files -u | grep -q .; then
    echo -e "${RED}!!! CONFLICTS REMAINING !!!${NC}"
    echo "Please resolve conflicts manually (e.g. in lib/...), then commit."
    echo "Note: Your protected paths ($PROTECTED_PATHS) have already been restored."
    exit 1
else
    echo -e "${GREEN}No conflicts or conflicts resolved.${NC}"
    # If we are in a merge state (MERGE_HEAD exists), commit it
    if [ -f .git/MERGE_HEAD ]; then
         git commit -m "chore: sync with upstream $(date +%Y-%m-%d) (preserve local customizations)"
         echo -e "${GREEN}Merge committed successfully!${NC}"
    else
         echo "Nothing to commit (already up to date)."
    fi
fi

echo -e "${GREEN}=== Synchronization Complete ===${NC}"

if [ "$STASH_NEEDED" = true ]; then
    echo -e "${BLUE}Restoring stashed changes...${NC}"
    if git stash pop; then
        echo -e "${GREEN}Local changes restored successfully.${NC}"
    else
        echo -e "${RED}Conflict detected while restoring stashed changes. Please resolve manually.${NC}"
    fi
fi