package solutions.bitbadger.documents.query

import solutions.bitbadger.documents.*

/**
 * Functions to create `WHERE` clause fragments
 */
object Where {

    /**
     * Create a `WHERE` clause fragment to query by one or more fields
     *
     * @param fields The fields to be queried
     * @param howMatched How the fields should be matched (optional, defaults to `ALL`)
     * @return A `WHERE` clause fragment to match the given fields
     */
    fun byFields(fields: Collection<Field<*>>, howMatched: FieldMatch? = null) =
        fields.joinToString(" ${(howMatched ?: FieldMatch.ALL).sql} ") { it.toWhere() }

    /**
     * Create a `WHERE` clause fragment to retrieve a document by its ID
     *
     * @param parameterName The parameter name to use for the ID placeholder (optional, defaults to ":id")
     * @param docId The ID value (optional; used for type determinations, string assumed if not provided)
     */
    fun <TKey> byId(parameterName: String = ":id", docId: TKey? = null) =
        byFields(listOf(Field.equal(Configuration.idField, docId ?: "", parameterName)))

    /**
     * Create a `WHERE` clause fragment to implement a JSON containment query (PostgreSQL only)
     *
     * @param parameterName The parameter name to use for the JSON placeholder (optional, defaults to ":criteria")
     * @return A `WHERE` clause fragment to implement a JSON containment criterion
     * @throws DocumentException If called against a SQLite database
     */
    fun jsonContains(parameterName: String = ":criteria") =
        when (Configuration.dialect("create containment WHERE clause")) {
            Dialect.POSTGRESQL -> "data @> $parameterName"
            Dialect.SQLITE     -> throw DocumentException("JSON containment is not supported")
        }

    /**
     * Create a `WHERE` clause fragment to implement a JSON path match query (PostgreSQL only)
     *
     * @param parameterName The parameter name to use for the placeholder (optional, defaults to ":path")
     * @return A `WHERE` clause fragment to implement a JSON path match criterion
     * @throws DocumentException If called against a SQLite database
     */
    fun jsonPathMatches(parameterName: String = ":path") =
        when (Configuration.dialect("create JSON path match WHERE clause")) {
            Dialect.POSTGRESQL -> "jsonb_path_exists(data, $parameterName::jsonpath)"
            Dialect.SQLITE     -> throw DocumentException("JSON path match is not supported")
        }
}