#!/bin/bash
# Validates that new migrations in a PR have timestamps greater than
# the latest migration timestamp on the master branch.
#
# This prevents migration ordering conflicts when multiple PRs add migrations.
# Modified existing migrations only produce warnings, not errors.

set -e

# Get the latest migration timestamp from master branch
# Filter for files matching the pattern: 14-digit timestamp followed by _ and ending in .sql or .go
MASTER_MIGRATIONS=$(git ls-tree --name-only origin/master -- db/migrations/ | grep -E '^db/migrations/[0-9]{14}_.*\.(sql|go)$' || true)

if [ -z "$MASTER_MIGRATIONS" ]; then
    echo "No migrations found on master branch"
    exit 0
fi

MASTER_LATEST=$(echo "$MASTER_MIGRATIONS" | sed 's|db/migrations/||' | cut -c1-14 | sort -n | tail -1)

# Get NEW migrations (added in this PR)
NEW_MIGRATIONS=$(git diff --name-only --diff-filter=A origin/master -- db/migrations/ | grep -E '^db/migrations/[0-9]{14}_.*\.(sql|go)$' || true)

# Get MODIFIED migrations (existing files that were changed)
MODIFIED_MIGRATIONS=$(git diff --name-only --diff-filter=M origin/master -- db/migrations/ | grep -E '^db/migrations/[0-9]{14}_.*\.(sql|go)$' || true)

if [ -z "$NEW_MIGRATIONS" ] && [ -z "$MODIFIED_MIGRATIONS" ]; then
    echo "No new or modified migrations found in this PR"
    exit 0
fi

echo "Latest migration on master: $MASTER_LATEST"

HAS_ERRORS=false

# Check NEW migrations - these MUST have valid timestamps (errors)
if [ -n "$NEW_MIGRATIONS" ]; then
    echo ""
    echo "New migrations in this PR:"
    for migration in $NEW_MIGRATIONS; do
        TIMESTAMP=$(basename "$migration" | cut -c1-14)
        echo "  - $migration (timestamp: $TIMESTAMP)"
        
        if [ "$TIMESTAMP" -le "$MASTER_LATEST" ]; then
            echo "::error file=$migration::Migration timestamp $TIMESTAMP must be greater than latest master timestamp $MASTER_LATEST"
            HAS_ERRORS=true
        fi
    done
fi

# Check MODIFIED migrations - only warn, don't fail
if [ -n "$MODIFIED_MIGRATIONS" ]; then
    echo ""
    echo "Modified existing migrations in this PR:"
    for migration in $MODIFIED_MIGRATIONS; do
        TIMESTAMP=$(basename "$migration" | cut -c1-14)
        echo "  - $migration (timestamp: $TIMESTAMP)"
        echo "::warning file=$migration::Modifying existing migration files may cause issues for users who have already applied them"
    done

    # Post a PR review comment if running in GitHub Actions with a PR
    if [ -n "$GITHUB_TOKEN" ] && [ -n "$GITHUB_REPOSITORY" ] && [ -n "$PR_NUMBER" ]; then
        COMMENT_BODY="### ⚠️ Modified Migration Files Detected

This PR modifies existing migration files that may have already been applied by users:

$(for m in $MODIFIED_MIGRATIONS; do echo "- \`$m\`"; done)

**Warning:** Modifying migrations that have already been applied can cause issues for existing users. Please ensure this change is intentional and consider the impact on users who have already run these migrations."

        # Use GitHub API to post a PR comment
        curl -s -X POST \
            -H "Authorization: token $GITHUB_TOKEN" \
            -H "Accept: application/vnd.github.v3+json" \
            "https://api.github.com/repos/$GITHUB_REPOSITORY/issues/$PR_NUMBER/comments" \
            -d "$(jq -n --arg body "$COMMENT_BODY" '{body: $body}')" > /dev/null
        
        echo "Posted PR comment about modified migrations"
    fi
fi

if [ "$HAS_ERRORS" = "true" ]; then
    echo ""
    echo "ERROR: One or more NEW migrations have timestamps that are not after the latest migration on master."
    echo "Please regenerate the migration with a newer timestamp using:"
    echo "  make migration-sql name=your_migration_name"
    echo "  make migration-go name=your_migration_name"
    exit 1
fi

echo ""
echo "All migration timestamps are valid!"