import type { ISODate, ISOTime, ISODatetime }  from "@/tsat/types";
import type {
    Att,
    AttValue,
    AttMultiple,
    AttStringDomain,
    AttNumberDomain,
    AttCurrencyDomain,
    AttBooleanDomain,
    AttOptionDomain,
    OptID, DomainValidationResult, DomainViolation, AttOpt,
} from "./types";


// ─────────────────────────────────────────────────────────────────────────────
// HELPERS
// ─────────────────────────────────────────────────────────────────────────────

const ok:  DomainValidationResult = { valid: true };

function err(reason: DomainViolation): DomainValidationResult {
    return { valid: false, level: 'error', reason };
}

/**
 * Valida la cardinalidad de un valor contra la configuración `multiple`.
 * Si no hay `multiple`, el valor debe ser escalar (no array).
 */
function validateMultiple(
    value:    unknown,
    multiple: AttMultiple | undefined,
): DomainValidationResult | null {

    if (multiple === undefined) {
        if (Array.isArray(value)) {
            return err({ code: 'SINGLE_NOT_SCALAR', value });
        }
        return null;
    }

    if (!Array.isArray(value)) {
        return err({ code: 'MULTIPLE_NOT_ARRAY', value });
    }

    if (value.length < multiple.min) {
        return err({ code: 'MULTIPLE_TOO_FEW', count: value.length, min: multiple.min });
    }

    if (value.length > multiple.max) {
        return err({ code: 'MULTIPLE_TOO_MANY', count: value.length, max: multiple.max });
    }

    return null;
}

function toArray(value: unknown): unknown[] {
    return Array.isArray(value) ? value : [value];
}

// ─────────────────────────────────────────────────────────────────────────────
// VALIDATORS POR KIND
// ─────────────────────────────────────────────────────────────────────────────

function validateString(
    domain: AttStringDomain,
    value:  unknown,
): DomainValidationResult {

    const cardinalityResult = validateMultiple(
        value,
        domain.mode !== 'fixed' ? domain.multiple : undefined,
    );
    if (cardinalityResult) return cardinalityResult;

    for (const v of toArray(value)) {
        if (typeof v !== 'string') {
            return err({ code: 'WRONG_TYPE', value: v, expected: 'string' });
        }

        if (domain.mode === 'list' && !domain.list.includes(v)) {
            return err({ code: 'VALUE_NOT_IN_LIST', value: v, list: domain.list });
        }

        if (domain.mode === 'pattern' && !new RegExp(domain.pattern).test(v)) {
            return err({ code: 'VALUE_PATTERN_MISMATCH', value: v, pattern: domain.pattern });
        }

        if (domain.mode === 'fixed' && v !== domain.fixed) {
            return err({ code: 'VALUE_NOT_IN_LIST', value: v, list: [domain.fixed] });
        }
    }

    return ok;
}

function validateNumber(
    domain: AttNumberDomain | AttCurrencyDomain,
    value:  unknown,
): DomainValidationResult {

    const cardinalityResult = validateMultiple(
        value,
        domain.mode !== 'fixed' ? domain.multiple : undefined,
    );
    if (cardinalityResult) return cardinalityResult;

    for (const v of toArray(value)) {
        if (typeof v !== 'number' || isNaN(v)) {
            return err({ code: 'WRONG_TYPE', value: v, expected: 'number' });
        }

        if (domain.mode === 'range' && (v < domain.min || v > domain.max)) {
            return err({ code: 'VALUE_OUT_OF_RANGE', value: v, min: domain.min, max: domain.max });
        }

        if (domain.mode === 'step') {
            if (v < domain.min || v > domain.max) {
                return err({ code: 'VALUE_OUT_OF_RANGE', value: v, min: domain.min, max: domain.max });
            }
            // Tolerancia flotante para evitar errores de precisión
            const steps   = (v - domain.min) / domain.step;
            const rounded = Math.round(steps);
            if (Math.abs(steps - rounded) > 1e-9) {
                return err({ code: 'VALUE_STEP_MISMATCH', value: v, min: domain.min, step: domain.step });
            }
        }

        if (domain.mode === 'list' && !domain.list.includes(v)) {
            return err({ code: 'VALUE_NOT_IN_LIST', value: v, list: domain.list });
        }

        if (domain.mode === 'fixed' && v !== domain.fixed) {
            return err({ code: 'VALUE_NOT_IN_LIST', value: v, list: [domain.fixed] });
        }
    }

    return ok;
}

function validateBoolean(
    domain: AttBooleanDomain,
    value:  unknown,
): DomainValidationResult {

    if (typeof value !== 'boolean') {
        return err({ code: 'WRONG_TYPE', value, expected: 'boolean' });
    }

    if (domain.mode === 'fixed' && value !== domain.fixed) {
        return err({ code: 'VALUE_NOT_IN_LIST', value, list: [domain.fixed] });
    }

    return ok;
}

function validateOption(
    domain: AttOptionDomain,
    value:  unknown,
): DomainValidationResult {

    const cardinalityResult = validateMultiple(
        value,
        domain.mode !== 'fixed' ? domain.multiple : undefined,
    );
    if (cardinalityResult) return cardinalityResult;

    for (const v of toArray(value)) {
        if (typeof v !== 'string') {
            return err({ code: 'WRONG_TYPE', value: v, expected: 'OptID' });
        }

        if (domain.mode === 'list') {
            const optIds = domain.list.map(o => o.optId);
            if (!optIds.includes(v as OptID)) {
                return err({ code: 'VALUE_NOT_IN_LIST', value: v, list: optIds });
            }
        }

        if (domain.mode === 'fixed' && v !== domain.fixed) {
            return err({ code: 'VALUE_NOT_IN_LIST', value: v, list: [domain.fixed] });
        }
    }

    return ok;
}

/**
 * Valida un string con formato ISO (date, time, datetime).
 * La validación de formato es estructural — no semántica (ej. no valida
 * que el 31 de febrero no existe).
 */
function validateISOString(
    domain:   { mode: string; multiple?: AttMultiple } & (
        | { mode: 'range'; min: string; max: string }
        | { mode: 'list';  list: string[] }
        | { mode: 'fixed'; fixed: string }
        | { mode: 'input' }
        ),
    value:    unknown,
    expected: string,
): DomainValidationResult {

    const cardinalityResult = validateMultiple(
        value,
        domain.mode !== 'fixed' ? domain.multiple : undefined,
    );
    if (cardinalityResult) return cardinalityResult;

    for (const v of toArray(value)) {
        if (typeof v !== 'string') {
            return err({ code: 'WRONG_TYPE', value: v, expected });
        }

        if (domain.mode === 'range' && (v < domain.min || v > domain.max)) {
            return err({ code: 'VALUE_OUT_OF_RANGE', value: v, min: domain.min, max: domain.max });
        }

        if (domain.mode === 'list' && !(domain.list as string[]).includes(v)) {
            return err({ code: 'VALUE_NOT_IN_LIST', value: v, list: domain.list });
        }

        if (domain.mode === 'fixed' && v !== domain.fixed) {
            return err({ code: 'VALUE_NOT_IN_LIST', value: v, list: [domain.fixed] });
        }
    }

    return ok;
}

// ─────────────────────────────────────────────────────────────────────────────
// ENTRY POINT
// ─────────────────────────────────────────────────────────────────────────────

/**
 * Valida un `AttValue` contra su dominio declarado (capa 0).
 *
 * Esta función es:
 * - **Pura** — sin efectos secundarios
 * - **Sin contexto** — no depende del estado del configurador
 * - **Determinista** — mismo input, mismo output siempre
 *
 * Solo valida que el valor sea estructuralmente coherente con el dominio.
 * La validación dinámica (reglas, dominio efectivo) es responsabilidad
 * del motor de evaluación (capa 1).
 *
 * @example
 * validateAttValue({
 *   domain: { kind: 'string', mode: 'list', list: ['tela', 'piel'] },
 *   value:  'madera'
 * })
 * // → { valid: false, level: 'error', reason: { code: 'VALUE_NOT_IN_LIST', ... } }
 */
export function validateAttValue(attValue: AttValue): DomainValidationResult {
    const { domain, value } = attValue;

    switch (domain.kind) {
        case 'string':
            return validateString(domain, value as unknown);

        case 'number':
        case 'currency':
            return validateNumber(domain, value as unknown);

        case 'boolean':
            return validateBoolean(domain, value as unknown);

        case 'option':
            return validateOption(domain, value as unknown);

        case 'date':
            return validateISOString(domain, value as unknown, 'ISODate');

        case 'time':
            return validateISOString(domain, value as unknown, 'ISOTime');

        case 'datetime':
            return validateISOString(domain, value as unknown, 'ISODatetime');

        default: {
            const _exhaustiveCheck: never = domain;
            throw new Error(`Unhandled domain kind: ${(_exhaustiveCheck as any).kind}`);
        }
    }
}

/**
 * Valida todos los atributos de un `Att` de forma directa.
 * Wrapper de conveniencia sobre `validateAttValue`.
 */
export function validateAtt(att: Att): DomainValidationResult {
    return validateAttValue(att.value);
}