function parseCommaSeparated(value) {
    if (!value) return [];
    return value
        .split(',')
        .map((v) => v.trim())
        .filter(Boolean);
}

function normalizeScope(scope) {
    if (!scope) return 'openid profile email';

    const normalized = scope.trim().split(/\s+/).filter(Boolean).join(' ');

    if (!normalized.includes('openid')) {
        console.warn(
            `OIDC scope does not include 'openid'. Adding it automatically. Original scope: "${scope}"`
        );
        return `openid ${normalized}`;
    }

    return normalized;
}

function loadProvidersFromEnv() {
    if (process.env.OIDC_ENABLED !== 'true') {
        console.log(
            'OIDC is disabled. Set OIDC_ENABLED=true to enable SSO authentication.'
        );
        return [];
    }

    const providers = [];

    let i = 1;
    while (process.env[`OIDC_PROVIDER_${i}_NAME`]) {
        const provider = {
            slug: process.env[`OIDC_PROVIDER_${i}_SLUG`],
            name: process.env[`OIDC_PROVIDER_${i}_NAME`],
            issuer: process.env[`OIDC_PROVIDER_${i}_ISSUER`],
            clientId: process.env[`OIDC_PROVIDER_${i}_CLIENT_ID`],
            clientSecret: process.env[`OIDC_PROVIDER_${i}_CLIENT_SECRET`],
            scope: normalizeScope(process.env[`OIDC_PROVIDER_${i}_SCOPE`]),
            autoProvision:
                process.env[`OIDC_PROVIDER_${i}_AUTO_PROVISION`] !== 'false',
            adminEmailDomains: parseCommaSeparated(
                process.env[`OIDC_PROVIDER_${i}_ADMIN_EMAIL_DOMAINS`]
            ),
        };

        const missingFields = [];
        if (!provider.slug) missingFields.push(`OIDC_PROVIDER_${i}_SLUG`);
        if (!provider.name) missingFields.push(`OIDC_PROVIDER_${i}_NAME`);
        if (!provider.issuer) missingFields.push(`OIDC_PROVIDER_${i}_ISSUER`);
        if (!provider.clientId)
            missingFields.push(`OIDC_PROVIDER_${i}_CLIENT_ID`);
        if (!provider.clientSecret)
            missingFields.push(`OIDC_PROVIDER_${i}_CLIENT_SECRET`);

        if (missingFields.length > 0) {
            console.warn(
                `Skipping OIDC provider ${i} due to missing required fields: ${missingFields.join(', ')}`
            );
            i++;
            continue;
        }

        console.log(`Loaded OIDC provider ${i}: ${provider.name}`);
        providers.push(provider);
        i++;
    }

    if (providers.length === 0 && process.env.OIDC_PROVIDER_NAME) {
        const provider = {
            slug: process.env.OIDC_PROVIDER_SLUG || 'default',
            name: process.env.OIDC_PROVIDER_NAME,
            issuer: process.env.OIDC_ISSUER_URL,
            clientId: process.env.OIDC_CLIENT_ID,
            clientSecret: process.env.OIDC_CLIENT_SECRET,
            scope: normalizeScope(process.env.OIDC_SCOPE),
            autoProvision: process.env.OIDC_AUTO_PROVISION !== 'false',
            adminEmailDomains: parseCommaSeparated(
                process.env.OIDC_ADMIN_EMAIL_DOMAINS
            ),
        };

        const missingFields = [];
        if (!provider.issuer) missingFields.push('OIDC_ISSUER_URL');
        if (!provider.clientId) missingFields.push('OIDC_CLIENT_ID');
        if (!provider.clientSecret) missingFields.push('OIDC_CLIENT_SECRET');

        if (missingFields.length > 0) {
            console.error(
                `Cannot load OIDC provider "${provider.name}": missing required fields: ${missingFields.join(', ')}`
            );
            return [];
        }

        console.log(`Loaded OIDC provider: ${provider.name}`);
        providers.push(provider);
    }

    if (providers.length === 0) {
        console.warn(
            'OIDC is enabled but no valid providers are configured. Please check your environment variables.'
        );
    }

    return providers;
}

let cachedProviders = null;

function getAllProviders() {
    if (!cachedProviders) {
        cachedProviders = loadProvidersFromEnv();
    }
    return cachedProviders;
}

function getProvider(slug) {
    const providers = getAllProviders();
    const provider = providers.find((p) => p.slug === slug);

    if (!provider) {
        return null;
    }

    return provider;
}

function isOidcEnabled() {
    return process.env.OIDC_ENABLED === 'true' && getAllProviders().length > 0;
}

function reloadProviders() {
    cachedProviders = null;
    return getAllProviders();
}

module.exports = {
    getAllProviders,
    getProvider,
    isOidcEnabled,
    reloadProviders,
};