"""
Verification script for PostgreSQL Task 3: Employee Hierarchy Management
"""

import os
import sys
import psycopg2
from decimal import Decimal

def rows_match(actual_row, expected_row):
    """
    Compare two rows with appropriate tolerance.
    For Decimal types: allows 0.01 tolerance
    For other types: requires exact match
    """
    if len(actual_row) != len(expected_row):
        return False
    
    for actual, expected in zip(actual_row, expected_row):
        if isinstance(actual, Decimal) and isinstance(expected, Decimal):
            if abs(float(actual) - float(expected)) > 0.01:
                return False
        elif actual != expected:
            return False
    
    return True

def get_connection_params() -> dict:
    """Get database connection parameters."""
    return {
        "host": os.getenv("POSTGRES_HOST", "localhost"),
        "port": int(os.getenv("POSTGRES_PORT", 5432)),
        "database": os.getenv("POSTGRES_DATABASE"),
        "user": os.getenv("POSTGRES_USERNAME"),
        "password": os.getenv("POSTGRES_PASSWORD")
    }

def verify_employee_count_and_titles(conn) -> bool:
    """Verify the final employee count and title changes."""
    with conn.cursor() as cur:
        # Check the final verification query results
        cur.execute("""
            SELECT 
                COUNT(*) as total_employees,
                COUNT(CASE WHEN "Title" = 'CEO' THEN 1 END) as ceo_count,
                COUNT(CASE WHEN "Title" = 'IT Specialist' THEN 1 END) as it_specialist_count,
                COUNT(CASE WHEN "ReportsTo" = 1 THEN 1 END) as reports_to_ceo
            FROM "Employee"
        """)
        result = cur.fetchone()
        
        total_employees, ceo_count, it_specialist_count, reports_to_ceo = result
        
        # Expected: total_employees = 9, ceo_count = 1, it_specialist_count = 1, reports_to_ceo = 4
        if total_employees != 9:
            print(f"❌ Expected 9 total employees, got {total_employees}")
            return False
            
        if ceo_count != 1:
            print(f"❌ Expected 1 CEO, got {ceo_count}")
            return False
            
        if it_specialist_count != 0:
            print(f"❌ Expected 0 IT Specialists, got {it_specialist_count}")
            return False
            
        if reports_to_ceo != 4:
            print(f"❌ Expected 4 employees reporting to CEO, got {reports_to_ceo}")
            return False
        
        print("✅ Employee count and title verification passed")
        return True

def verify_specific_employees(conn) -> bool:
    """Verify specific employee records and modifications."""
    with conn.cursor() as cur:
        # Check all employee fields in one query
        cur.execute("""
            SELECT "EmployeeId", "LastName", "FirstName", "Title", "ReportsTo", "BirthDate", 
                   "HireDate", "Address", "City", "State", "Country", "PostalCode", 
                   "Phone", "Fax", "Email"
            FROM "Employee" 
            WHERE "EmployeeId" IN (1, 2, 9, 10)
            ORDER BY "EmployeeId"
        """)
        employees = cur.fetchall()
        
        from datetime import datetime
        
        expected = [
            # Andrew Adams (ID 1) - Title changes to 'CEO', phone stays original, ReportsTo stays None
            (1, 'Adams', 'Andrew', 'CEO', None, datetime(1962, 2, 18), datetime(2002, 8, 14),
             '11120 Jasper Ave NW', 'Edmonton', 'AB', 'Canada', 'T5K 2N1', '+1 (780) 428-9482', '+1 (780) 428-3457', 'andrew@chinookcorp.com'),
            # Nancy Edwards (ID 2) - Phone changes, title stays 'Sales Manager', ReportsTo stays 1
            (2, 'Edwards', 'Nancy', 'Sales Manager', 1, datetime(1958, 12, 8), datetime(2002, 5, 1),
             '825 8 Ave SW', 'Calgary', 'AB', 'Canada', 'T2P 2T3', '+1 (403) 555-9999', '+1 (403) 262-3322', 'nancy@chinookcorp.com'),
            # Sarah Johnson - all new data, final ReportsTo = 1 (changed in step 4)
            (9, 'Johnson', 'Sarah', 'Sales Support Agent', 1, datetime(1985, 3, 15), datetime(2009, 1, 10),
             '123 Oak Street', 'Calgary', 'AB', 'Canada', 'T2P 5G3', '+1 (403) 555-0123', '+1 (403) 555-0124', 'sarah.johnson@chinookcorp.com'),
            # Mike Chen - all new data, final ReportsTo = 1 (changed in step 4)
            (10, 'Chen', 'Mike', 'Sales Support Agent', 1, datetime(1982, 8, 22), datetime(2009, 1, 10),
             '456 Pine Ave', 'Calgary', 'AB', 'Canada', 'T2P 5G4', '+1 (403) 555-0125', '+1 (403) 555-0126', 'mike.chen@chinookcorp.com')
        ]
        
        if len(employees) != 4:
            print(f"❌ Expected 4 key employees, found {len(employees)}")
            return False
            
        # Full field comparison for all employees using rows_match
        for actual, expected_emp in zip(employees, expected):
            if not rows_match(actual, expected_emp):
                print(f"❌ Employee {actual[0]} row mismatch: expected {expected_emp}, got {actual}")
                return False
        
        print("✅ Specific employee verification passed - all fields match exactly")
        return True

def verify_customer_assignments(conn) -> bool:
    """Verify customer support representative assignments."""
    with conn.cursor() as cur:
        # Check customers 1, 2, 3 are assigned to Sarah (ID 9)
        cur.execute("""
            SELECT COUNT(*)
            FROM "Customer" 
            WHERE "CustomerId" IN (1, 2, 3) AND "SupportRepId" = 9
        """)
        sarah_customers = cur.fetchone()[0]
        
        if sarah_customers != 3:
            print(f"❌ Expected 3 customers assigned to Sarah Johnson, got {sarah_customers}")
            return False
        
        # Check customers 4, 5, 6 are assigned to Mike (ID 10)
        cur.execute("""
            SELECT COUNT(*)
            FROM "Customer" 
            WHERE "CustomerId" IN (4, 5, 6) AND "SupportRepId" = 10
        """)
        mike_customers = cur.fetchone()[0]
        
        if mike_customers != 3:
            print(f"❌ Expected 3 customers assigned to Mike Chen, got {mike_customers}")
            return False
        
        print("✅ Customer assignment verification passed")
        return True

def verify_performance_table(conn) -> bool:
    """Verify the employee_performance table exists and has correct data."""
    with conn.cursor() as cur:
        try:
            # Get all performance records
            cur.execute("""
                SELECT employee_id, customers_assigned, performance_score
                FROM employee_performance 
                ORDER BY employee_id
            """)
            actual_results = cur.fetchall()
            
            # Get actual customer counts for verification
            cur.execute("""
                SELECT "SupportRepId", COUNT(*) 
                FROM "Customer" 
                WHERE "SupportRepId" IN (9, 10)
                GROUP BY "SupportRepId"
                ORDER BY "SupportRepId"
            """)
            customer_counts = dict(cur.fetchall())
            
            expected = [
                (9, customer_counts.get(9, 0), Decimal('4.5')),  # Sarah Johnson
                (10, customer_counts.get(10, 0), Decimal('4.2'))  # Mike Chen
            ]
            
            if len(actual_results) != 2:
                print(f"❌ Expected 2 performance records, got {len(actual_results)}")
                return False
            
            for actual, expected_row in zip(actual_results, expected):
                if not rows_match(actual, expected_row):
                    print(f"❌ Performance record mismatch: expected {expected_row}, got {actual}")
                    return False
            
            print("✅ Employee performance table verification passed")
            return True
            
        except psycopg2.Error as e:
            print(f"❌ Employee performance table verification failed: {e}")
            return False

def verify_employee_deletion_and_promotion(conn) -> bool:
    """Verify Robert King deletion and Laura Callahan promotion."""
    with conn.cursor() as cur:
        try:
            # Verify Robert King (ID 7) is deleted
            cur.execute("""
                SELECT COUNT(*) FROM "Employee" WHERE "EmployeeId" = 7
            """)
            if cur.fetchone()[0] != 0:
                print("❌ Robert King (EmployeeId = 7) should be deleted")
                return False
            
            # Verify Laura Callahan (ID 8) promotion
            cur.execute("""
                SELECT "Title" FROM "Employee" WHERE "EmployeeId" = 8
            """)
            laura_title = cur.fetchone()
            if not laura_title or laura_title[0] != 'Senior IT Specialist':
                print(f"❌ Laura Callahan should have title 'Senior IT Specialist', got: {laura_title[0] if laura_title else None}")
                return False
            
            print("✅ Employee deletion and promotion verification passed")
            return True
            
        except psycopg2.Error as e:
            print(f"❌ Employee deletion/promotion verification failed: {e}")
            return False

def verify_salary_column(conn) -> bool:
    """Verify salary column exists and has correct values."""
    with conn.cursor() as cur:
        try:
            # Check if salary column exists and get all salary values
            cur.execute("""
                SELECT "EmployeeId", salary 
                FROM "Employee" 
                ORDER BY "EmployeeId"
            """)
            salary_data = cur.fetchall()
            
            # Verify Laura (ID 8) has 75000.00, others have 50000.00
            for emp_id, salary in salary_data:
                expected_salary = Decimal('75000.00') if emp_id == 8 else Decimal('50000.00')
                if salary != expected_salary:
                    print(f"❌ Employee {emp_id} salary should be {expected_salary}, got {salary}")
                    return False
            
            print("✅ Salary column verification passed")
            return True
            
        except psycopg2.Error as e:
            print(f"❌ Salary column verification failed: {e}")
            return False

def main():
    """Main verification function."""
    print("=" * 50)
    print("Verifying Task 3: Employee Hierarchy Management")
    print("=" * 50)

    # Get connection parameters
    conn_params = get_connection_params()

    if not conn_params["database"]:
        print("❌ No database specified")
        sys.exit(1)

    try:
        # Connect to database
        conn = psycopg2.connect(**conn_params)

        # Run verification checks with short-circuit evaluation
        success = (verify_employee_count_and_titles(conn) and
                  verify_specific_employees(conn) and
                  verify_customer_assignments(conn) and
                  verify_performance_table(conn) and
                  verify_employee_deletion_and_promotion(conn) and
                  verify_salary_column(conn))

        conn.close()

        if success:
            print("\n🎉 Task verification: PASS")
            print("All employee hierarchy management operations completed correctly!")
            sys.exit(0)
        else:
            print("\n❌ Task verification: FAIL")
            sys.exit(1)

    except psycopg2.Error as e:
        print(f"❌ Database error: {e}")
        sys.exit(1)
    except Exception as e:
        print(f"❌ Verification error: {e}")
        sys.exit(1)

if __name__ == "__main__":
    main()