//! End-to-end federation scenario tests
//!
//! Tests for realistic multi-subgraph federation scenarios:
//! - Single-database federation
//! - Multi-database federation
//! - Cross-subgraph relationships
//! - Complex queries

use fraiseql_core::federation::types::{FederatedType, FederationMetadata, KeyDirective};
use serde_json::json;

// ============================================================================
// Single Database Federation Scenarios
// ============================================================================

#[test]
fn test_single_database_single_subgraph() {
    // Single PostgreSQL database, single FraiseQL subgraph
    let metadata = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![
            FederatedType {
                name:                "User".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          false,
                external_fields:     vec![],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
            FederatedType {
                name:                "Order".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          false,
                external_fields:     vec![],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
        ],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    assert!(metadata.enabled);
    assert_eq!(metadata.types.len(), 2);

    // Both types are owned locally
    for fed_type in &metadata.types {
        assert!(!fed_type.is_extends, "All types owned by single subgraph");
    }
}

#[test]
fn test_multiple_database_same_subgraph() {
    // Multiple databases (PostgreSQL + MySQL) in single subgraph
    // (Configuration would specify different connection pools, not reflected in metadata)
    let metadata = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![
            FederatedType {
                name:                "User".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          false,
                external_fields:     vec![],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
            FederatedType {
                name:                "Analytics".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          false,
                external_fields:     vec![],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
        ],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    // Same subgraph owns both types
    for fed_type in &metadata.types {
        assert!(!fed_type.is_extends);
    }
}

// ============================================================================
// Multi-Subgraph Federation Scenarios
// ============================================================================

#[test]
fn test_two_subgraph_federation() {
    // Scenario: Subgraph 1 owns User, Subgraph 2 extends User and owns Order

    // Subgraph 1 metadata
    let subgraph1 = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![FederatedType {
            name:                "User".to_string(),
            keys:                vec![KeyDirective {
                fields:     vec!["id".to_string()],
                resolvable: true,
            }],
            is_extends:          false,
            external_fields:     vec![],
            shareable_fields:    vec![],
            inaccessible_fields: vec![],
            field_directives:    std::collections::HashMap::new(),
            type_shareable:      false,
        }],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    // Subgraph 2 metadata
    let subgraph2 = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![
            FederatedType {
                name:                "User".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          true,
                external_fields:     vec!["email".to_string()],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
            FederatedType {
                name:                "Order".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          false,
                external_fields:     vec![],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
        ],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    // Verify Subgraph 1 owns User
    assert!(!subgraph1.types[0].is_extends);

    // Verify Subgraph 2 extends User and owns Order
    assert!(subgraph2.types[0].is_extends);
    assert!(!subgraph2.types[1].is_extends);
}

#[test]
fn test_three_subgraph_federation() {
    // Scenario: Users | Orders | Products federation

    let users_subgraph = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![FederatedType {
            name:                "User".to_string(),
            keys:                vec![KeyDirective {
                fields:     vec!["id".to_string()],
                resolvable: true,
            }],
            is_extends:          false,
            external_fields:     vec![],
            shareable_fields:    vec![],
            inaccessible_fields: vec![],
            field_directives:    std::collections::HashMap::new(),
            type_shareable:      false,
        }],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    let orders_subgraph = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![
            FederatedType {
                name:                "User".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          true,
                external_fields:     vec!["email".to_string()],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
            FederatedType {
                name:                "Order".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          false,
                external_fields:     vec![],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
        ],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    let products_subgraph = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![
            FederatedType {
                name:                "Order".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          true,
                external_fields:     vec!["userId".to_string()],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
            FederatedType {
                name:                "Product".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          false,
                external_fields:     vec![],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
        ],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    // Verify ownership hierarchy
    assert!(!users_subgraph.types[0].is_extends);
    assert!(orders_subgraph.types[0].is_extends);
    assert!(!orders_subgraph.types[1].is_extends);
    assert!(products_subgraph.types[0].is_extends);
    assert!(!products_subgraph.types[1].is_extends);
}

// ============================================================================
// Composite Key Federation Scenarios
// ============================================================================

#[test]
fn test_multi_tenant_federation() {
    // Multi-tenant SaaS: composite key (tenantId, userId)
    let metadata = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![FederatedType {
            name:                "TenantUser".to_string(),
            keys:                vec![KeyDirective {
                fields:     vec!["tenantId".to_string(), "userId".to_string()],
                resolvable: true,
            }],
            is_extends:          false,
            external_fields:     vec![],
            shareable_fields:    vec![],
            inaccessible_fields: vec![],
            field_directives:    std::collections::HashMap::new(),
            type_shareable:      false,
        }],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    let key = &metadata.types[0].keys[0];
    assert_eq!(key.fields.len(), 2);
    assert_eq!(key.fields[0], "tenantId");
    assert_eq!(key.fields[1], "userId");
}

#[test]
fn test_organization_user_order_federation() {
    // Composite keys: (organizationId, userId) for User, (organizationId, orderId) for Order

    let user_type = FederatedType {
        name:                "OrgUser".to_string(),
        keys:                vec![KeyDirective {
            fields:     vec!["organizationId".to_string(), "userId".to_string()],
            resolvable: true,
        }],
        is_extends:          false,
        external_fields:     vec![],
        shareable_fields:    vec![],
        inaccessible_fields: vec![],
        field_directives:    std::collections::HashMap::new(),
        type_shareable:      false,
    };

    let order_type = FederatedType {
        name:                "OrgOrder".to_string(),
        keys:                vec![KeyDirective {
            fields:     vec!["organizationId".to_string(), "orderId".to_string()],
            resolvable: true,
        }],
        is_extends:          false,
        external_fields:     vec![],
        shareable_fields:    vec![],
        inaccessible_fields: vec![],
        field_directives:    std::collections::HashMap::new(),
        type_shareable:      false,
    };

    assert_eq!(user_type.keys[0].fields.len(), 2);
    assert_eq!(order_type.keys[0].fields.len(), 2);
}

// ============================================================================
// Cross-Subgraph Relationship Scenarios
// ============================================================================

#[test]
fn test_user_order_relationship() {
    // User -> Order relationship across subgraphs

    // Subgraph 1: owns User
    let user_metadata = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![FederatedType {
            name:                "User".to_string(),
            keys:                vec![KeyDirective {
                fields:     vec!["id".to_string()],
                resolvable: true,
            }],
            is_extends:          false,
            external_fields:     vec![],
            shareable_fields:    vec![],
            inaccessible_fields: vec![],
            field_directives:    std::collections::HashMap::new(),
            type_shareable:      false,
        }],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    // Subgraph 2: owns Order, references User
    let order_metadata = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![
            FederatedType {
                name:                "User".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          true,
                external_fields:     vec!["email".to_string()],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
            FederatedType {
                name:                "Order".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          false,
                external_fields:     vec![],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
        ],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    // User is owned by subgraph 1
    assert!(!user_metadata.types[0].is_extends);

    // User is extended by subgraph 2
    assert!(order_metadata.types[0].is_extends);

    // Order is owned by subgraph 2
    assert!(!order_metadata.types[1].is_extends);
}

#[test]
fn test_user_order_product_relationship() {
    // User -> Order -> Product relationship

    let users_sg = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![FederatedType {
            name:                "User".to_string(),
            keys:                vec![KeyDirective {
                fields:     vec!["id".to_string()],
                resolvable: true,
            }],
            is_extends:          false,
            external_fields:     vec![],
            shareable_fields:    vec![],
            inaccessible_fields: vec![],
            field_directives:    std::collections::HashMap::new(),
            type_shareable:      false,
        }],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    let orders_sg = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![
            FederatedType {
                name:                "User".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          true,
                external_fields:     vec!["email".to_string()],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
            FederatedType {
                name:                "Order".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          false,
                external_fields:     vec![],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
        ],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    let products_sg = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![
            FederatedType {
                name:                "Order".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          true,
                external_fields:     vec!["userId".to_string()],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
            FederatedType {
                name:                "Product".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          false,
                external_fields:     vec![],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
        ],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    // Verify ownership chain: User (users_sg) -> Order (orders_sg) -> Product (products_sg)
    assert!(!users_sg.types[0].is_extends); // User owned
    assert!(orders_sg.types[0].is_extends); // User extended
    assert!(!orders_sg.types[1].is_extends); // Order owned
    assert!(products_sg.types[0].is_extends); // Order extended
    assert!(!products_sg.types[1].is_extends); // Product owned
}

// ============================================================================
// Shareable Field Scenarios
// ============================================================================

#[test]
fn test_shareable_field_resolution() {
    // Field can be resolved by multiple subgraphs
    let metadata = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![FederatedType {
            name:                "Product".to_string(),
            keys:                vec![KeyDirective {
                fields:     vec!["id".to_string()],
                resolvable: true,
            }],
            is_extends:          false,
            external_fields:     vec![],
            shareable_fields:    vec!["price".to_string(), "name".to_string()],
            inaccessible_fields: vec![],
            field_directives:    std::collections::HashMap::new(),
            type_shareable:      false,
        }],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    let product_type = &metadata.types[0];
    assert!(product_type.shareable_fields.contains(&"price".to_string()));
    assert!(product_type.shareable_fields.contains(&"name".to_string()));
}

// ============================================================================
// Query Routing Scenarios
// ============================================================================

#[test]
fn test_single_subgraph_query() {
    // Query: { user(id: "1") { id name email } }
    // Resolution: Local (Subgraph 1 owns User)

    let metadata = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![FederatedType {
            name:                "User".to_string(),
            keys:                vec![KeyDirective {
                fields:     vec!["id".to_string()],
                resolvable: true,
            }],
            is_extends:          false,
            external_fields:     vec![],
            shareable_fields:    vec![],
            inaccessible_fields: vec![],
            field_directives:    std::collections::HashMap::new(),
            type_shareable:      false,
        }],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    // User is locally owned
    let user_type = &metadata.types[0];
    assert!(!user_type.is_extends);
}

#[test]
fn test_two_subgraph_join_query() {
    // Query: { order(id: "1") { id user { name } } }
    // Resolution:
    // - Order: Local (Subgraph 2)
    // - User: Remote (Subgraph 1)

    let user_metadata = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![FederatedType {
            name:                "User".to_string(),
            keys:                vec![KeyDirective {
                fields:     vec!["id".to_string()],
                resolvable: true,
            }],
            is_extends:          false,
            external_fields:     vec![],
            shareable_fields:    vec![],
            inaccessible_fields: vec![],
            field_directives:    std::collections::HashMap::new(),
            type_shareable:      false,
        }],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    let order_metadata = FederationMetadata {
        enabled: true,
        version: "v2".to_string(),
        types: vec![
            FederatedType {
                name:                "User".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          true,
                external_fields:     vec!["email".to_string()],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
            FederatedType {
                name:                "Order".to_string(),
                keys:                vec![KeyDirective {
                    fields:     vec!["id".to_string()],
                    resolvable: true,
                }],
                is_extends:          false,
                external_fields:     vec![],
                shareable_fields:    vec![],
                inaccessible_fields: vec![],
                field_directives:    std::collections::HashMap::new(),
                type_shareable:      false,
            },
        ],
        remote_subscription_fields: std::collections::HashMap::new(),
    };

    // Order is local in order_metadata
    assert!(!order_metadata.types[1].is_extends);

    // User must be fetched from user_metadata
    assert!(!user_metadata.types[0].is_extends);
}

// ============================================================================
// Error Scenarios
// ============================================================================

#[test]
fn test_entity_not_found_scenario() {
    // When entity cannot be found, federation returns null
    let entity_response = json!(null);

    assert!(entity_response.is_null());
}

#[test]
fn test_partial_entity_resolution_scenario() {
    // Some entities found, some not found
    let responses = [
        json!({"id": "1", "name": "Alice"}),
        json!(null), // Not found
        json!({"id": "3", "name": "Charlie"}),
    ];

    let found_count = responses.iter().filter(|r| r.is_object()).count();
    let null_count = responses.iter().filter(|r| r.is_null()).count();

    assert_eq!(found_count, 2);
    assert_eq!(null_count, 1);
}
