#!/bin/bash
# .githooks/post-checkout
# Git hook for BMAD-METHOD contributors to provide sync reminders
#
# This hook provides helpful reminders when:
# 1. Switching to main branch
# 2. Switching from main to feature branch
# 3. Creating new branches

# Color codes for output
RED='\033[0;31m'
YELLOW='\033[1;33m'
GREEN='\033[0;32m'
BLUE='\033[0;34m'
NC='\033[0m' # No Color

# Configuration
UPSTREAM_REMOTE="upstream"
MAIN_BRANCH="main"

# Arguments passed by git
# $1: ref of previous HEAD
# $2: ref of new HEAD
# $3: flag indicating branch checkout (1) or file checkout (0)
PREV_HEAD=$1
NEW_HEAD=$2
BRANCH_CHECKOUT=$3

# Only run for branch checkouts, not file checkouts
if [ "$BRANCH_CHECKOUT" != "1" ]; then
    exit 0
fi

# Get branch names
NEW_BRANCH=$(git branch --show-current)
PREV_BRANCH=$(git reflog -1 | grep -oP 'moving from \K[^ ]+' || echo "")

# Skip if we couldn't determine branches
if [ -z "$NEW_BRANCH" ]; then
    exit 0
fi

echo -e "${BLUE}[post-checkout] Switched to branch: $NEW_BRANCH${NC}"

# Check if upstream remote exists
HAS_UPSTREAM=false
if git remote | grep -q "^${UPSTREAM_REMOTE}$"; then
    HAS_UPSTREAM=true
fi

# Case 1: Switched TO main branch
if [ "$NEW_BRANCH" = "$MAIN_BRANCH" ]; then
    echo ""
    if [ "$HAS_UPSTREAM" = true ]; then
        # Check if main is behind upstream
        git fetch "$UPSTREAM_REMOTE" --quiet 2>/dev/null || true
        LOCAL_MAIN=$(git rev-parse "$MAIN_BRANCH" 2>/dev/null || echo "")
        UPSTREAM_MAIN=$(git rev-parse "${UPSTREAM_REMOTE}/${MAIN_BRANCH}" 2>/dev/null || echo "")
        
        if [ -n "$LOCAL_MAIN" ] && [ -n "$UPSTREAM_MAIN" ]; then
            if [ "$LOCAL_MAIN" != "$UPSTREAM_MAIN" ]; then
                if git merge-base --is-ancestor "$LOCAL_MAIN" "$UPSTREAM_MAIN"; then
                    echo -e "${YELLOW}💡 Your local '$MAIN_BRANCH' is behind upstream${NC}"
                    echo -e "${YELLOW}   Sync with: git pull $UPSTREAM_REMOTE $MAIN_BRANCH${NC}"
                elif ! git merge-base --is-ancestor "$UPSTREAM_MAIN" "$LOCAL_MAIN"; then
                    echo -e "${RED}⚠️  Your local '$MAIN_BRANCH' has diverged from upstream${NC}"
                    echo -e "${YELLOW}   Reset with: git reset --hard $UPSTREAM_REMOTE/$MAIN_BRANCH${NC}"
                else
                    echo -e "${GREEN}✓ Your local '$MAIN_BRANCH' is synced with upstream${NC}"
                fi
            else
                echo -e "${GREEN}✓ Your local '$MAIN_BRANCH' is synced with upstream${NC}"
            fi
        fi
    else
        echo -e "${YELLOW}💡 Tip: Add upstream remote for easier syncing:${NC}"
        echo -e "   git remote add $UPSTREAM_REMOTE git@github.com:bmad-code-org/BMAD-METHOD.git"
    fi
    echo ""
fi

# Case 2: Switched FROM main to feature branch
if [ "$PREV_BRANCH" = "$MAIN_BRANCH" ] && [ "$NEW_BRANCH" != "$MAIN_BRANCH" ]; then
    echo ""
    if [ "$HAS_UPSTREAM" = true ]; then
        # Check if current branch is based on latest main
        MERGE_BASE=$(git merge-base "$NEW_BRANCH" "$MAIN_BRANCH" 2>/dev/null || echo "")
        MAIN_HEAD=$(git rev-parse "$MAIN_BRANCH" 2>/dev/null || echo "")
        
        if [ -n "$MERGE_BASE" ] && [ -n "$MAIN_HEAD" ] && [ "$MERGE_BASE" != "$MAIN_HEAD" ]; then
            echo -e "${YELLOW}💡 This branch may need rebasing on latest '$MAIN_BRANCH'${NC}"
            echo -e "   Rebase with: git rebase $MAIN_BRANCH"
        fi
    fi
    
    # Remind about single-commit workflow
    COMMIT_COUNT=$(git rev-list --count "${MAIN_BRANCH}..${NEW_BRANCH}" 2>/dev/null || echo "0")
    if [ "$COMMIT_COUNT" -gt 1 ]; then
        echo -e "${YELLOW}💡 This branch has $COMMIT_COUNT commits${NC}"
        echo -e "${YELLOW}   Remember to maintain single-commit workflow before pushing${NC}"
        echo -e "   Squash with: git reset --soft $MAIN_BRANCH && git commit"
    fi
    echo ""
fi

# Case 3: Creating a new branch (both refs are the same)
if [ "$PREV_HEAD" = "$NEW_HEAD" ] && [ "$PREV_BRANCH" != "$NEW_BRANCH" ]; then
    echo ""
    echo -e "${GREEN}✓ New branch created: $NEW_BRANCH${NC}"
    echo -e "${BLUE}💡 Remember the single-commit workflow:${NC}"
    echo -e "   1. Make your changes"
    echo -e "   2. Commit once: git commit -m 'feat: description'"
    echo -e "   3. Update with: git commit --amend (not new commits)"
    echo -e "   4. Push with: git push --force-with-lease"
    echo ""
fi

# General reminder for feature branches (not main)
if [ "$NEW_BRANCH" != "$MAIN_BRANCH" ]; then
    # Check if hooks are configured
    CURRENT_HOOKS_PATH=$(git config core.hooksPath || echo "")
    if [ "$CURRENT_HOOKS_PATH" != ".githooks" ]; then
        echo -e "${YELLOW}💡 Tip: Enable git hooks with:${NC}"
        echo -e "   git config core.hooksPath .githooks"
        echo ""
    fi
fi

exit 0