import {Service} from '../../../di/src/decorator/Service.ts'
import {Canonical} from './Canonical.ts'

export class DuplicateResolverKeyError extends Error {
    constructor(key: string) {
        super(`There is already a canonical unit with the scope ${key} registered.`)
    }
}

export class NoSuchCanonicalResolverKeyError extends Error {
    constructor(key: string) {
        super(`There is no such canonical unit with the scope ${key} registered.`)
    }

}

@Service()
export class Canon {
    protected resources: { [key: string]: Canonical<any> } = {}

    resource<T>(key: string): Canonical<T> {
        if ( !this.resources[key] ) throw new NoSuchCanonicalResolverKeyError(key)
        return this.resources[key] as Canonical<T>
    }

    register_canonical(unit: Canonical<any>) {
        const key = unit.canonical_items
        if ( this.resources[key] ) throw new DuplicateResolverKeyError(key)
        this.resources[key] = unit
    }
}