/**
 * Conditional Validation - Revolutionary dependent field validation
 * 
 * This module provides powerful conditional validation where fields can depend
 * on other fields' values, making complex business logic validation simple.
 */

import { SchemaInterface } from "../mode/interfaces/Interface";

/**
 * Conditional validation utilities
 */
export const When = {
    /**
     * Create conditional validation based on another field's value
     * 
     * @example
     * ```typescript
     * const UserSchema = Interface({
     *   accountType: Make.union("free", "premium", "enterprise"),
     *   maxProjects: When.field("accountType").is("free").then("int(1,3)")
     *                   .is("premium").then("int(1,50)")
     *                   .is("enterprise").then("int(1,)")
     *                   .default("int(1,1)"),
     *   
     *   paymentMethod: When.field("accountType").isNot("free").then("string").else("string?"),
     *   billingAddress: When.field("paymentMethod").exists().then({
     *     street: "string",
     *     city: "string",
     *     country: "string(2,2)"
     *   }).else("any?")
     * });
     * ```
     */
    field(fieldName: string): ConditionalBuilder {
        return new ConditionalBuilder(fieldName);
    },

    /**
     * Create validation that depends on multiple fields
     * 
     * @example
     * ```typescript
     * const OrderSchema = Interface({
     *   orderType: Make.union("pickup", "delivery"),
     *   address: "string?",
     *   deliveryFee: "number?",
     *   
     *   // Complex conditional validation
     *   ...When.fields(["orderType", "address"]).match({
     *     orderType: "delivery",
     *     address: (val) => val && val.length > 0
     *   }).then({
     *     deliveryFee: "number(0,)"  // Required for delivery with address
     *   }).else({
     *     deliveryFee: "number?"     // Optional otherwise
     *   })
     * });
     * ```
     */
    fields(fieldNames: string[]): MultiConditionalBuilder {
        return new MultiConditionalBuilder(fieldNames);
    },

    /**
     * Create custom validation logic
     * 
     * @example
     * ```typescript
     * const EventSchema = Interface({
     *   startDate: "date",
     *   endDate: "date",
     *   
     *   // Custom validation: endDate must be after startDate
     *   ...When.custom((data) => {
     *     if (data.endDate <= data.startDate) {
     *       return { error: "End date must be after start date" };
     *     }
     *     return { valid: true };
     *   })
     * });
     * ```
     */
    custom(validator: (data: any) => { valid: true } | { error: string }): CustomValidator {
        return new CustomValidator(validator);
    }
};

/**
 * Builder for single field conditional validation
 */
class ConditionalBuilder {
    private conditions: Array<{
        condition: (value: any) => boolean;
        schema: any;
    }> = [];
    private defaultSchema: any = null;

    constructor(private fieldName: string) {}

    /**
     * Check if field equals specific value
     */
    is(value: any): ConditionalThen {
        return new ConditionalThen(this, (fieldValue) => fieldValue === value);
    }

    /**
     * Check if field does not equal specific value
     */
    isNot(value: any): ConditionalThen {
        return new ConditionalThen(this, (fieldValue) => fieldValue !== value);
    }

    /**
     * Check if field exists (not null/undefined)
     */
    exists(): ConditionalThen {
        return new ConditionalThen(this, (fieldValue) => fieldValue != null);
    }

    /**
     * Check if field matches pattern
     */
    matches(pattern: RegExp): ConditionalThen {
        return new ConditionalThen(this, (fieldValue) => 
            typeof fieldValue === "string" && pattern.test(fieldValue)
        );
    }

    /**
     * Check if field is in array of values
     */
    in(values: any[]): ConditionalThen {
        return new ConditionalThen(this, (fieldValue) => values.includes(fieldValue));
    }

    /**
     * Custom condition function
     */
    when(condition: (value: any) => boolean): ConditionalThen {
        return new ConditionalThen(this, condition);
    }

    addCondition(condition: (value: any) => boolean, schema: any): this {
        this.conditions.push({ condition, schema });
        return this;
    }

    default(schema: any): any {
        this.defaultSchema = schema;
        return this.build();
    }

    build(): any {
        // Return a special object that the validation engine can recognize
        return {
            __conditional: true,
            fieldName: this.fieldName,
            conditions: this.conditions,
            default: this.defaultSchema
        };
    }
}

/**
 * Builder for the "then" part of conditional validation
 */
class ConditionalThen {
    constructor(
        private builder: ConditionalBuilder,
        private condition: (value: any) => boolean
    ) {}

    then(schema: any): ConditionalBuilder {
        return this.builder.addCondition(this.condition, schema);
    }
}

/**
 * Builder for multi-field conditional validation
 */
class MultiConditionalBuilder {
    private matchConditions: any = {};

    constructor(private fieldNames: string[]) {}

    match(conditions: Record<string, any>): MultiConditionalThen {
        this.matchConditions = conditions;
        return new MultiConditionalThen(this, conditions);
    }
}

/**
 * Builder for multi-field "then" part
 */
class MultiConditionalThen {
    constructor(
        private builder: MultiConditionalBuilder,
        private conditions: Record<string, any>
    ) {}

    then(schema: any): MultiConditionalElse {
        return new MultiConditionalElse(schema, null);
    }
}

/**
 * Builder for multi-field "else" part
 */
class MultiConditionalElse {
    constructor(
        private thenSchema: any,
        private elseSchema: any
    ) {}

    else(schema: any): any {
        return {
            __multiConditional: true,
            then: this.thenSchema,
            else: schema
        };
    }
}

/**
 * Custom validator builder
 */
class CustomValidator {
    constructor(private validator: (data: any) => { valid: true } | { error: string }) {}

    build(): any {
        return {
            __customValidator: true,
            validator: this.validator
        };
    }
}

/**
 * Revolutionary schema composition with inheritance
 */
export const Extend = {
    /**
     * Create schema inheritance with method-like syntax
     * 
     * @example
     * ```typescript
     * const BaseEntitySchema = Interface({
     *   id: "uuid",
     *   createdAt: "date",
     *   updatedAt: "date"
     * }); 
     *  
     * const UserSchema = Extend.from(BaseEntitySchema).with({
     *   email: "email",
     *   username: "string(3,20)",
     *   profile: {
     *     firstName: "string",
     *     lastName: "string"
     *   }
     * });
     * 
     * const AdminSchema = Extend.from(UserSchema).with({
     *   permissions: "string[]",
     *   role: Make.const("admin")
     * }).override({
     *   email: "email(,254)"  // Override with more specific validation
     * });
     * ```
     */
    from(baseSchema: SchemaInterface): ExtendBuilder {
        return new ExtendBuilder(baseSchema);
    }
};

/**
 * Builder for schema extension
 */
class ExtendBuilder {
    constructor(private baseSchema: SchemaInterface) {}

    with(additionalFields: any): ExtendWithBuilder {
        return new ExtendWithBuilder(this.baseSchema, additionalFields);
    }
}

/**
 * Builder for extended schema with additional methods
 */
class ExtendWithBuilder {
    constructor(
        private baseSchema: SchemaInterface,
        private additionalFields: any
    ) {}

    override(overrides: any): SchemaInterface {
        // Merge base schema, additional fields, and overrides
        return {
            ...this.baseSchema,
            ...this.additionalFields,
            ...overrides
        } as SchemaInterface;
    }

    build(): SchemaInterface {
        return {
            ...this.baseSchema,
            ...this.additionalFields
        } as SchemaInterface;
    }
}

/**
 * Export all utilities
 */
export { ConditionalBuilder, MultiConditionalBuilder, CustomValidator, ExtendBuilder };
export default When;