#!/bin/bash
# Backup Verification Script
# Checks backup health, integrity, and provides status report

set -e

# Configuration
PROJECT_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
BACKUP_ROOT="$PROJECT_ROOT/backups"

# Colors
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m'

# Counters
TOTAL_BACKUPS=0
VALID_BACKUPS=0
CORRUPTED_BACKUPS=0
WARNINGS=0

echo -e "${BLUE}=== Backup Verification Report ===${NC}\n"
echo "Generated: $(date)"
echo "Backup location: $BACKUP_ROOT"
echo ""

# Function to verify a single backup
verify_single_backup() {
    local backup_file="$1"
    TOTAL_BACKUPS=$((TOTAL_BACKUPS + 1))

    if tar -tzf "$backup_file" > /dev/null 2>&1; then
        VALID_BACKUPS=$((VALID_BACKUPS + 1))
        return 0
    else
        CORRUPTED_BACKUPS=$((CORRUPTED_BACKUPS + 1))
        echo -e "  ${RED}✗ CORRUPTED: $backup_file${NC}"
        return 1
    fi
}

# Check daily backups
echo -e "${YELLOW}Daily Backups:${NC}"
if [ -d "$BACKUP_ROOT/daily" ]; then
    DAILY_COUNT=$(ls "$BACKUP_ROOT/daily"/*.tar.gz 2>/dev/null | wc -l)
    echo "  Found: $DAILY_COUNT backups"

    if [ "$DAILY_COUNT" -eq 0 ]; then
        echo -e "  ${RED}⚠ WARNING: No daily backups found${NC}"
        WARNINGS=$((WARNINGS + 1))
    else
        # Check latest backup age
        LATEST=$(ls -t "$BACKUP_ROOT/daily"/*.tar.gz 2>/dev/null | head -n 1)
        AGE_HOURS=$(( ($(date +%s) - $(stat -c %Y "$LATEST" 2>/dev/null || stat -f %m "$LATEST")) / 3600 ))
        echo "  Latest backup: $(basename "$LATEST")"
        echo "  Age: ${AGE_HOURS} hours ago"

        if [ "$AGE_HOURS" -gt 24 ]; then
            echo -e "  ${RED}⚠ WARNING: Latest backup is >24 hours old${NC}"
            WARNINGS=$((WARNINGS + 1))
        fi

        # Verify integrity
        for backup in "$BACKUP_ROOT/daily"/*.tar.gz; do
            verify_single_backup "$backup" > /dev/null
        done
        echo -e "  ${GREEN}✓ All daily backups verified${NC}"
    fi
else
    echo -e "  ${RED}✗ Daily backup directory not found${NC}"
    WARNINGS=$((WARNINGS + 1))
fi

echo ""

# Check weekly backups
echo -e "${YELLOW}Weekly Backups:${NC}"
if [ -d "$BACKUP_ROOT/weekly" ]; then
    WEEKLY_COUNT=$(ls "$BACKUP_ROOT/weekly"/*.tar.gz 2>/dev/null | wc -l)
    echo "  Found: $WEEKLY_COUNT backups"

    if ls "$BACKUP_ROOT/weekly"/*.tar.gz 1> /dev/null 2>&1; then
        for backup in "$BACKUP_ROOT/weekly"/*.tar.gz; do
            verify_single_backup "$backup" > /dev/null
        done
    fi

    if [ "$WEEKLY_COUNT" -gt 0 ]; then
        echo -e "  ${GREEN}✓ All weekly backups verified${NC}"
    fi
else
    echo "  No weekly backups directory"
fi

echo ""

# Check monthly backups
echo -e "${YELLOW}Monthly Backups:${NC}"
if [ -d "$BACKUP_ROOT/monthly" ]; then
    MONTHLY_COUNT=$(ls "$BACKUP_ROOT/monthly"/*.tar.gz 2>/dev/null | wc -l)
    echo "  Found: $MONTHLY_COUNT backups"

    if ls "$BACKUP_ROOT/monthly"/*.tar.gz 1> /dev/null 2>&1; then
        for backup in "$BACKUP_ROOT/monthly"/*.tar.gz; do
            verify_single_backup "$backup" > /dev/null
        done
    fi

    if [ "$MONTHLY_COUNT" -gt 0 ]; then
        echo -e "  ${GREEN}✓ All monthly backups verified${NC}"
    fi
else
    echo "  No monthly backups directory"
fi

echo ""

# Storage usage
echo -e "${YELLOW}Storage Usage:${NC}"
if [ -d "$BACKUP_ROOT" ]; then
    TOTAL_SIZE=$(du -sh "$BACKUP_ROOT" 2>/dev/null | cut -f1)
    echo "  Total backup size: $TOTAL_SIZE"

    # Check if approaching limits (>5GB)
    SIZE_MB=$(du -sm "$BACKUP_ROOT" 2>/dev/null | cut -f1)
    if [ "$SIZE_MB" -gt 5120 ]; then
        echo -e "  ${YELLOW}⚠ WARNING: Backup storage >5GB, consider cleanup${NC}"
        WARNINGS=$((WARNINGS + 1))
    fi
fi

echo ""

# Check disk space
echo -e "${YELLOW}Disk Space:${NC}"
DISK_USAGE=$(df -h "$BACKUP_ROOT" | tail -1)
DISK_PERCENT=$(echo "$DISK_USAGE" | awk '{print $5}' | sed 's/%//')
echo "  Disk usage: $DISK_PERCENT%"

if [ "$DISK_PERCENT" -gt 80 ]; then
    echo -e "  ${RED}⚠ WARNING: Disk usage >80%${NC}"
    WARNINGS=$((WARNINGS + 1))
fi

echo ""

# Summary
echo -e "${BLUE}=== Summary ===${NC}"
echo "Total backups checked: $TOTAL_BACKUPS"
echo -e "Valid backups: ${GREEN}$VALID_BACKUPS${NC}"

if [ "$CORRUPTED_BACKUPS" -gt 0 ]; then
    echo -e "Corrupted backups: ${RED}$CORRUPTED_BACKUPS${NC}"
fi

if [ "$WARNINGS" -gt 0 ]; then
    echo -e "Warnings: ${YELLOW}$WARNINGS${NC}"
fi

echo ""

# Final status
if [ "$CORRUPTED_BACKUPS" -eq 0 ] && [ "$WARNINGS" -eq 0 ] && [ "$VALID_BACKUPS" -gt 0 ]; then
    echo -e "${GREEN}✓ Backup system healthy${NC}"
    exit 0
elif [ "$CORRUPTED_BACKUPS" -gt 0 ]; then
    echo -e "${RED}✗ CRITICAL: Corrupted backups detected${NC}"
    exit 2
elif [ "$WARNINGS" -gt 0 ]; then
    echo -e "${YELLOW}⚠ Backup system has warnings${NC}"
    exit 1
else
    echo -e "${YELLOW}⚠ No backups found - run initial backup${NC}"
    exit 1
fi