import { computed, inject, Injectable, signal } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { firstValueFrom } from 'rxjs';
import { NGXLogger } from 'ngx-logger';
import { BASE_HREF } from '../../utils';
import { Router } from '@angular/router';

export interface IBaseTenant {
    readonly tenantId: string;
    readonly displayName: string;
    readonly guid: string;
}

@Injectable({ providedIn: 'root' })
export class TenantsService {
    readonly tenants = signal<IBaseTenant[] | undefined>(undefined);
    readonly hasMultiple = computed(() => {
        const tenants = this.tenants();
        return tenants ? tenants.length > 1 : false;
    });
    readonly #http = inject(HttpClient);
    readonly #router = inject(Router);
    readonly #logger = inject(NGXLogger);
    readonly #baseHref = inject(BASE_HREF);
    readonly #storageReference: Storage = {
        length: localStorage.length,
        clear: localStorage.clear.bind(localStorage),
        getItem: localStorage.getItem.bind(localStorage),
        setItem: localStorage.setItem.bind(localStorage),
        removeItem: localStorage.removeItem.bind(localStorage),
        key: localStorage.key.bind(localStorage),
    };
    readonly #activeTenantId = signal<string>('');

    get currentTenant() {
        return this.#activeTenantId();
    }

    async loadTenants() {
        this.#logger.info('[TENANTS] Loading tenants...');
        const tenants = await firstValueFrom(this.#http.get<IBaseTenant[]>('/tenants/simple'));
        this.tenants.set(tenants);

        const tenant = this.getTenantFromRoute();
        if (tenant) {
            this.#logger.info('[TENANTS] Tenant from route: ', tenant);
            if (await this.selectTenant(tenant)) {
                await this.#executeMainResolverAndRedirect(tenant);
            }
            return;
        }

        this.#logger.info('[TENANTS] No tenant in route');

        if (!this.hasMultiple) {
            this.#logger.info('[TENANTS] Only one tenant loaded, auto-select it and redirect to login page');
            const tenant = tenants[0].tenantId;
            if (await this.selectTenant(tenant)) {
                await this.#executeMainResolverAndRedirect(tenant);
            }
        }
    }

    getTenantFromRoute() {
        const path = window.location.pathname;
        const nextSlash = path.indexOf('/', this.#baseHref.length + 1);
        return path.substring(this.#baseHref.length + 1, nextSlash >= 0 ? nextSlash : path.length);
    }

    async selectTenant(tenantId: string) {
        const tenants = this.tenants();
        if (!tenants) {
            throw new Error('Tenants not loaded!');
        }

        const unknownTenant = !tenants.map(t => t.tenantId).includes(tenantId);

        if (unknownTenant) {
            this.#logger.info('[TENANTS] Unknown tenant, redirecting to select tenant page');
            await this.#router.navigate(['/']);
            return false;
        }

        this.#mutateStorage(tenantId);
        this.#setCurrentTenantId(tenantId);
        return true;
    }

    #setCurrentTenantId(tenantId: string) {
        this.#logger.info('[TENANTS] Set current tenant id: ', tenantId);
        this.#activeTenantId.set(tenantId);
    }

    #mutateStorage(tenant: string) {
        localStorage.getItem = (key: string) => {
            return this.#storageReference.getItem(tenant + ':' + key);
        };
        localStorage.setItem = (key: string, value: string) => {
            this.#storageReference.setItem(tenant + ':' + key, value);
        };
        localStorage.removeItem = (key: string) => {
            this.#storageReference.removeItem(tenant + ':' + key);
        };
    }

    async #executeMainResolverAndRedirect(tenant: string) {
        const intendedPath = window.location.pathname.replace(this.#baseHref, '');
        // TODO: Load roles in child routes canLoad functions so we can redirect straight to wanted URL
        await this.#router.navigate([tenant], { skipLocationChange: true });
        await this.#router.navigate([intendedPath]);
    }
}