//
// Copyright Amazon.com Inc. or its affiliates.
// All Rights Reserved.
//
// SPDX-License-Identifier: Apache-2.0
//

import Amplify
import Foundation
import SQLite

/// Represents a `delete` SQL statement that is optionally composed by a `ConditionStatement`.
struct DeleteStatement: SQLStatement {

    let modelSchema: ModelSchema
    let conditionStatement: ConditionStatement?
    let namespace = "root"

    init(modelSchema: ModelSchema, predicate: QueryPredicate? = nil) {
        self.modelSchema = modelSchema

        var conditionStatement: ConditionStatement?
        if let predicate = predicate {
            let statement = ConditionStatement(modelSchema: modelSchema,
                                               predicate: predicate,
                                               namespace: namespace[...])
            conditionStatement = statement
        }
        self.conditionStatement = conditionStatement
    }

    init<M: Model>(_: M.Type,
                   modelSchema: ModelSchema,
                   withId id: String,
                   predicate: QueryPredicate? = nil) {
        let identifier = DefaultModelIdentifier<M>.makeDefault(id: id)
        self.init(modelSchema: modelSchema,
                  withIdentifier: identifier,
                  predicate: predicate)
    }

    init(modelSchema: ModelSchema,
         withIdentifier id: ModelIdentifierProtocol,
         predicate: QueryPredicate? = nil) {
        var queryPredicate: QueryPredicate = field(modelSchema.primaryKey.sqlName)
            .eq(id.stringValue)
        if let predicate = predicate {
            queryPredicate = field(modelSchema.primaryKey.sqlName)
                .eq(id.stringValue).and(predicate)
        }
        self.init(modelSchema: modelSchema, predicate: queryPredicate)
    }

    init(model: Model) {
        self.init(modelSchema: model.schema)
    }

    var stringValue: String {
        let sql = """
        delete from "\(modelSchema.name)" as \(namespace)
        """

        if let conditionStatement = conditionStatement {
            return """
            \(sql)
            where 1 = 1
            \(conditionStatement.stringValue)
            """
        }
        return sql
    }

    var variables: [Binding?] {
        return conditionStatement?.variables ?? []
    }

}