/**
 * Cookie Consent Core
 * storage.js
 *
 * Cookie-based persistence for consent state.
 * This module deliberately contains no consent/business operations.
 */

const DEFAULT_COOKIE_NAME = "cc_consent";
const DEFAULT_DURATION_DAYS = 180;
const DEFAULT_PATH = "/";
const DEFAULT_SAME_SITE = "Lax";

function isBrowser() {
    return typeof document !== "undefined";
}

function encode(value) {
    return encodeURIComponent(value);
}

function decode(value) {
    try {
        return decodeURIComponent(value);
    } catch {
        return null;
    }
}

function buildAttributes(options = {}) {
    const {
        duration,
        path = DEFAULT_PATH,
        domain,
        sameSite = DEFAULT_SAME_SITE,
        secure,
        partitioned = false
    } = options;

    const attributes = [];

    if (typeof duration === "number" && Number.isFinite(duration)) {
        if (duration <= 0) {
            attributes.push("Max-Age=0");
        } else {
            const maxAge = Math.floor(duration * 24 * 60 * 60);
            attributes.push(`Max-Age=${maxAge}`);
        }
    }

    if (path) {
        attributes.push(`Path=${path}`);
    }

    if (domain) {
        attributes.push(`Domain=${domain}`);
    }

    if (sameSite) {
        attributes.push(`SameSite=${sameSite}`);
    }

    const shouldSecure =
        secure === true ||
        (secure === undefined &&
            typeof location !== "undefined" &&
            location.protocol === "https:");

    if (shouldSecure) {
        attributes.push("Secure");
    }

    if (partitioned) {
        attributes.push("Partitioned");
    }

    return attributes.join("; ");
}

export function createCookieStorage(options = {}) {
    const config = {
        name: options.name || DEFAULT_COOKIE_NAME,
        duration:
            typeof options.duration === "number"
                ? options.duration
                : DEFAULT_DURATION_DAYS,
        path: options.path || DEFAULT_PATH,
        domain: options.domain,
        sameSite: options.sameSite || DEFAULT_SAME_SITE,
        secure: options.secure,
        partitioned: options.partitioned === true
    };

    return Object.freeze({
        name: config.name,

        getRaw() {
            if (!isBrowser()) {
                return null;
            }

            const prefix = `${encode(config.name)}=`;
            const cookies = document.cookie ? document.cookie.split("; ") : [];

            for (const item of cookies) {
                if (item.startsWith(prefix)) {
                    return decode(item.slice(prefix.length));
                }
            }

            return null;
        },

        get() {
            const raw = this.getRaw();

            if (!raw) {
                return null;
            }

            try {
                return JSON.parse(raw);
            } catch {
                return null;
            }
        },

        set(payload) {
            if (!isBrowser()) {
                return false;
            }

            let serialized;

            try {
                serialized = JSON.stringify(payload);
            } catch {
                return false;
            }

            const attributes = buildAttributes(config);

            document.cookie =
                `${encode(config.name)}=${encode(serialized)}` +
                (attributes ? `; ${attributes}` : "");

            return this.getRaw() !== null;
        },

        remove() {
            if (!isBrowser()) {
                return false;
            }

            const attributes = buildAttributes({
                ...config,
                duration: 0
            });

            document.cookie =
                `${encode(config.name)}=` +
                (attributes ? `; ${attributes}` : "");

            return this.getRaw() === null;
        },

        getConfig() {
            return { ...config };
        }
    });
}

/**
 * Validates the persisted envelope before the consent engine attempts to
 * interpret its contents. Category semantics are validated separately.
 */
export function isStoragePayload(value) {
    if (!value || typeof value !== "object" || Array.isArray(value)) {
        return false;
    }

    if (typeof value.engineVersion !== "string" || !value.engineVersion) {
        return false;
    }

    if (typeof value.policyVersion !== "string" || !value.policyVersion) {
        return false;
    }

    if (!Number.isFinite(value.timestamp)) {
        return false;
    }

    if (!value.categories ||
        typeof value.categories !== "object" ||
        Array.isArray(value.categories)) {
        return false;
    }

    if (typeof value.jurisdiction !== "string" || !value.jurisdiction) {
        return false;
    }

    if (typeof value.gpc !== "boolean") {
        return false;
    }

    return true;
}

export const STORAGE_DEFAULTS = Object.freeze({
    name: DEFAULT_COOKIE_NAME,
    duration: DEFAULT_DURATION_DAYS,
    path: DEFAULT_PATH,
    sameSite: DEFAULT_SAME_SITE
});