#!/bin/bash

# Semantic commit pattern:
# feat|fix|docs|style|refactor|test|perf|build|ci|chore|revert(optional scope): message
# Allow dots (.), uppercase letters, and other common filename characters in scope
PATTERN='^(feat|fix|docs|style|refactor|test|perf|build|ci|chore|revert)(\([a-zA-Z0-9\-\.\_]+\))?: .{1,}$'

# Pattern for merge commits from pull requests - simplified to catch all formats
PR_MERGE_PATTERN='^Merge pull request'

# Pattern for standard Git merge commits
GIT_MERGE_PATTERN='^Merge (branch|remote-tracking branch) .+ into .+$'

# Set text colors
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[0;33m'
BLUE='\033[0;34m'
NC='\033[0m' # No Color

INVALID_COMMITS=0

# Read stdin (format: <old-value> <new-value> <ref-name>)
while read -r OLD_REV NEW_REV REF_NAME; do
    # Skip if it's a branch deletion
    if [[ "$NEW_REV" = "0000000000000000000000000000000000000000" ]]; then
        continue
    fi

    # Skip if it's a new branch (no old revision)
    if [[ "$OLD_REV" = "0000000000000000000000000000000000000000" ]]; then
        OLD_REV=$(git rev-list --max-parents=0 "$NEW_REV")
    fi

    echo -e "${YELLOW}Checking commits in $REF_NAME${NC}"

    # Get all commit hashes between old and new revision
    COMMITS=$(git rev-list "$OLD_REV".."$NEW_REV")

    # Check each commit message
    for COMMIT in $COMMITS; do
        COMMIT_MSG=$(git log --format=%B -n 1 "$COMMIT")
        COMMIT_SUBJECT=$(echo "$COMMIT_MSG" | head -n 1)
        PARENT_COUNT=$(git rev-list --parents -n 1 "$COMMIT" | awk '{print NF - 1}')

        # Skip validation for merge commits (both PR merges and standard Git merges)
        if [[ $PARENT_COUNT -gt 1 ]] && ([[ "$COMMIT_SUBJECT" =~ $PR_MERGE_PATTERN ]] || [[ "$COMMIT_SUBJECT" =~ $GIT_MERGE_PATTERN ]]); then
            echo -e "${BLUE}➜ Skipping merge commit:${NC} $COMMIT_SUBJECT"
            continue
        fi

        if ! [[ "$COMMIT_SUBJECT" =~ $PATTERN ]]; then
            echo -e "${RED}✗ Invalid commit message:${NC} $COMMIT_SUBJECT"
            echo -e "${RED}  Commit:${NC} $COMMIT"
            echo -e "${YELLOW}  Message should follow semantic commit format:${NC}"
            echo -e "  type(scope): message"
            echo -e "  ${YELLOW}where type is one of:${NC} feat, fix, docs, style, refactor, test, perf, build, ci, chore, revert"
            echo ""
            INVALID_COMMITS=$((INVALID_COMMITS + 1))
        else
            echo -e "${GREEN}✓ Valid commit:${NC} $COMMIT_SUBJECT"
        fi
    done
done

# If any commits were invalid, reject the push
if [[ $INVALID_COMMITS -gt 0 ]]; then
    echo -e "${RED}Push rejected: $INVALID_COMMITS commit(s) have invalid messages.${NC}"
    echo -e "${YELLOW}Please rewrite your commit messages to follow the semantic commit format:${NC}"
    echo "type(scope): message"
    echo "Examples:"
    echo "  feat(auth): add login with Google"
    echo "  fix: correct calculation in billing module"
    echo "  style(release.yml): format permissions section in YAML"
    exit 1
fi

exit 0