//
//  NSManagedObjectContext+Querying.swift
//  CoreStore
//
//  Copyright © 2018 John Rommel Estropia
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in all
//  copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
//  SOFTWARE.
//

import Foundation
import CoreData


// MARK: - NSManagedObjectContext

extension NSManagedObjectContext: FetchableSource, QueryableSource {
    
    // MARK: FetchableSource
    
    @nonobjc
    public func fetchExisting<O: DynamicObject>(_ object: O) -> O? {
        
        let rawObject = object.cs_toRaw()
        if rawObject.objectID.isTemporaryID {
            
            do {
                
                try withExtendedLifetime(self) { (context: NSManagedObjectContext) -> Void in
                    
                    try context.obtainPermanentIDs(for: [rawObject])
                }
            }
            catch {
                
                Internals.log(
                    CoreStoreError(error),
                    "Failed to obtain permanent ID for object."
                )
                return nil
            }
        }
        do {
            
            let existingRawObject = try self.existingObject(with: rawObject.objectID)
            if existingRawObject === rawObject {
                
                return object
            }
            return object.runtimeType().cs_fromRaw(object: existingRawObject)
        }
        catch {
            
            Internals.log(
                CoreStoreError(error),
                "Failed to load existing \(Internals.typeName(object)) in context."
            )
            return nil
        }
    }
    
    @nonobjc
    public func fetchExisting<O: DynamicObject>(_ objectID: NSManagedObjectID) -> O? {
        
        do {
            
            let existingObject = try self.existingObject(with: objectID)
            return O.cs_fromRaw(object: existingObject)
        }
        catch _ {
            
            return nil
        }
    }
    
    @nonobjc
    public func fetchExisting<O: DynamicObject, S: Sequence>(_ objects: S) -> [O] where S.Iterator.Element == O {
        
        return objects.compactMap({ self.fetchExisting($0.cs_id()) })
    }
    
    @nonobjc
    public func fetchExisting<O: DynamicObject, S: Sequence>(_ objectIDs: S) -> [O] where S.Iterator.Element == NSManagedObjectID {
        
        return objectIDs.compactMap({ self.fetchExisting($0) })
    }
    
    @nonobjc
    public func fetchOne<O>(_ from: From<O>, _ fetchClauses: FetchClause...) throws -> O? {
        
        return try self.fetchOne(from, fetchClauses)
    }
    
    @nonobjc
    public func fetchOne<O>(_ from: From<O>, _ fetchClauses: [FetchClause]) throws -> O? {
        
        let fetchRequest = Internals.CoreStoreFetchRequest<NSManagedObject>()
        try from.applyToFetchRequest(fetchRequest, context: self)
        
        fetchRequest.fetchLimit = 1
        fetchRequest.resultType = .managedObjectResultType
        fetchClauses.forEach { $0.applyToFetchRequest(fetchRequest) }

        return try self.fetchOne(fetchRequest).flatMap(from.entityClass.cs_fromRaw)
    }
    
    @nonobjc
    public func fetchOne<B: FetchChainableBuilderType>(_ clauseChain: B) throws -> B.ObjectType? {
        
        return try self.fetchOne(clauseChain.from, clauseChain.fetchClauses)
    }
    
    @nonobjc
    public func fetchAll<O>(_ from: From<O>, _ fetchClauses: FetchClause...) throws -> [O] {
        
        return try self.fetchAll(from, fetchClauses)
    }
    
    @nonobjc
    public func fetchAll<O>(_ from: From<O>, _ fetchClauses: [FetchClause]) throws -> [O] {
        
        let fetchRequest = Internals.CoreStoreFetchRequest<NSManagedObject>()
        try from.applyToFetchRequest(fetchRequest, context: self)
        
        fetchRequest.fetchLimit = 0
        fetchRequest.resultType = .managedObjectResultType
        fetchClauses.forEach { $0.applyToFetchRequest(fetchRequest) }

        let entityClass = from.entityClass
        return try self.fetchAll(fetchRequest).map(entityClass.cs_fromRaw)
    }
    
    @nonobjc
    public func fetchAll<B: FetchChainableBuilderType>(_ clauseChain: B) throws -> [B.ObjectType] {
        
        return try self.fetchAll(clauseChain.from, clauseChain.fetchClauses)
    }
    
    @nonobjc
    public func fetchCount<O>(_ from: From<O>, _ fetchClauses: FetchClause...) throws -> Int {
    
        return try self.fetchCount(from, fetchClauses)
    }
    
    @nonobjc
    public func fetchCount<O>(_ from: From<O>, _ fetchClauses: [FetchClause]) throws -> Int {
        
        let fetchRequest = Internals.CoreStoreFetchRequest<NSNumber>()
        try from.applyToFetchRequest(fetchRequest, context: self)

        fetchRequest.resultType = .countResultType
        fetchClauses.forEach { $0.applyToFetchRequest(fetchRequest) }

        return try self.fetchCount(fetchRequest)
    }
    
    @nonobjc
    public func fetchCount<B: FetchChainableBuilderType>(_ clauseChain: B) throws -> Int {
        
        return try self.fetchCount(clauseChain.from, clauseChain.fetchClauses)
    }
    
    @nonobjc
    public func fetchObjectID<O>(_ from: From<O>, _ fetchClauses: FetchClause...) throws -> NSManagedObjectID? {
        
        return try self.fetchObjectID(from, fetchClauses)
    }
    
    @nonobjc
    public func fetchObjectID<O>(_ from: From<O>, _ fetchClauses: [FetchClause]) throws -> NSManagedObjectID? {
        
        let fetchRequest = Internals.CoreStoreFetchRequest<NSManagedObjectID>()
        try from.applyToFetchRequest(fetchRequest, context: self)
        
        fetchRequest.fetchLimit = 1
        fetchRequest.resultType = .managedObjectIDResultType
        fetchClauses.forEach { $0.applyToFetchRequest(fetchRequest) }

        return try self.fetchObjectID(fetchRequest)
    }

    @nonobjc
    public func fetchObjectID<B: FetchChainableBuilderType>(_ clauseChain: B) throws -> NSManagedObjectID? {
        
        return try self.fetchObjectID(clauseChain.from, clauseChain.fetchClauses)
    }
    
    @nonobjc
    public func fetchObjectIDs<O>(_ from: From<O>, _ fetchClauses: FetchClause...) throws -> [NSManagedObjectID] {
        
        return try self.fetchObjectIDs(from, fetchClauses)
    }
    
    @nonobjc
    public func fetchObjectIDs<O>(_ from: From<O>, _ fetchClauses: [FetchClause]) throws -> [NSManagedObjectID] {

        let fetchRequest = Internals.CoreStoreFetchRequest<NSManagedObjectID>()
        try from.applyToFetchRequest(fetchRequest, context: self)
        
        fetchRequest.fetchLimit = 0
        fetchRequest.resultType = .managedObjectIDResultType
        fetchClauses.forEach { $0.applyToFetchRequest(fetchRequest) }

        return try self.fetchObjectIDs(fetchRequest)
    }

    @nonobjc
    public func fetchObjectIDs<B: FetchChainableBuilderType>(_ clauseChain: B) throws -> [NSManagedObjectID] {
        
        return try self.fetchObjectIDs(clauseChain.from, clauseChain.fetchClauses)
    }
    
    @nonobjc
    internal func fetchObjectIDs(_ fetchRequest: Internals.CoreStoreFetchRequest<NSManagedObjectID>) throws -> [NSManagedObjectID] {
        
        var fetchResults: [NSManagedObjectID]?
        var fetchError: Error?
        self.performAndWait {
            
            do {
                
                fetchResults = try self.fetch(fetchRequest.dynamicCast())
            }
            catch {
                
                fetchError = error
            }
        }
        if let fetchResults = fetchResults {

            return fetchResults
        }
        let coreStoreError = CoreStoreError(fetchError)
        Internals.log(
            coreStoreError,
            "Failed executing fetch request."
        )
        throw coreStoreError
    }
    
    
    // MARK: QueryableSource
    
    @nonobjc
    public func queryValue<O, U: QueryableAttributeType>(_ from: From<O>, _ selectClause: Select<O, U>, _ queryClauses: QueryClause...) throws -> U? {
        
        return try self.queryValue(from, selectClause, queryClauses)
    }
    
    @nonobjc
    public func queryValue<O, U: QueryableAttributeType>(_ from: From<O>, _ selectClause: Select<O, U>, _ queryClauses: [QueryClause]) throws -> U? {
        
        let fetchRequest = Internals.CoreStoreFetchRequest<NSDictionary>()
        try from.applyToFetchRequest(fetchRequest, context: self)
        
        fetchRequest.fetchLimit = 0
        
        selectClause.applyToFetchRequest(fetchRequest.staticCast())
        queryClauses.forEach { $0.applyToFetchRequest(fetchRequest) }

        return try self.queryValue(selectClause.selectTerms, fetchRequest: fetchRequest)
    }
    
    @nonobjc
    public func queryValue<B>(_ clauseChain: B) throws -> B.ResultType? where B: QueryChainableBuilderType, B.ResultType: QueryableAttributeType {
        
        return try self.queryValue(clauseChain.from, clauseChain.select, clauseChain.queryClauses)
    }
    
    @nonobjc
    public func queryAttributes<O>(_ from: From<O>, _ selectClause: Select<O, NSDictionary>, _ queryClauses: QueryClause...) throws -> [[String: Any]] {
        
        return try self.queryAttributes(from, selectClause, queryClauses)
    }
    
    @nonobjc
    public func queryAttributes<O>(_ from: From<O>, _ selectClause: Select<O, NSDictionary>, _ queryClauses: [QueryClause]) throws -> [[String: Any]] {
        
        let fetchRequest = Internals.CoreStoreFetchRequest<NSDictionary>()
        try from.applyToFetchRequest(fetchRequest, context: self)
        
        fetchRequest.fetchLimit = 0
        
        selectClause.applyToFetchRequest(fetchRequest.staticCast())
        queryClauses.forEach { $0.applyToFetchRequest(fetchRequest) }

        return try self.queryAttributes(fetchRequest)
    }
    
    public func queryAttributes<B>(_ clauseChain: B) throws -> [[String : Any]] where B : QueryChainableBuilderType, B.ResultType == NSDictionary {
        
        return try self.queryAttributes(clauseChain.from, clauseChain.select, clauseChain.queryClauses)
    }
    
    
    // MARK: FetchableSource, QueryableSource
    
    @nonobjc
    public func unsafeContext() -> NSManagedObjectContext {
        
        return self
    }
    
    
    // MARK: Deleting
    
    @nonobjc
    internal func deleteAll<O>(_ from: From<O>, _ deleteClauses: [FetchClause]) throws -> Int {
        
        let fetchRequest = Internals.CoreStoreFetchRequest<NSManagedObject>()
        try from.applyToFetchRequest(fetchRequest, context: self)
        
        fetchRequest.fetchLimit = 0
        fetchRequest.resultType = .managedObjectResultType
        fetchRequest.returnsObjectsAsFaults = true
        fetchRequest.includesPropertyValues = false
        deleteClauses.forEach { $0.applyToFetchRequest(fetchRequest) }

        return try self.deleteAll(fetchRequest)
    }
}


// MARK: - NSManagedObjectContext (Internal)

extension NSManagedObjectContext {
    
    // MARK: Fetching
    
    @nonobjc
    internal func fetchOne<O: NSManagedObject>(_ fetchRequest: Internals.CoreStoreFetchRequest<O>) throws -> O? {
        
        var fetchResults: [O]?
        var fetchError: Error?
        self.performAndWait {
            
            do {
                
                fetchResults = try self.fetch(fetchRequest.staticCast())
            }
            catch {
                
                fetchError = error
            }
        }
        if let fetchResults = fetchResults {

            return fetchResults.first
        }
        let coreStoreError = CoreStoreError(fetchError)
        Internals.log(
            coreStoreError,
            "Failed executing fetch request."
        )
        throw coreStoreError
    }
    
    @nonobjc
    internal func fetchAll<O: NSManagedObject>(_ fetchRequest: Internals.CoreStoreFetchRequest<O>) throws -> [O] {
        
        var fetchResults: [O]?
        var fetchError: Error?
        self.performAndWait {
            
            do {
                
                fetchResults = try self.fetch(fetchRequest.staticCast())
            }
            catch {
                
                fetchError = error
            }
        }
        if let fetchResults = fetchResults {

            return fetchResults
        }
        let coreStoreError = CoreStoreError(fetchError)
        Internals.log(
            coreStoreError,
            "Failed executing fetch request."
        )
        throw coreStoreError
    }
    
    @nonobjc
    internal func fetchCount(_ fetchRequest: Internals.CoreStoreFetchRequest<NSNumber>) throws -> Int {
        
        var count = 0
        var countError: Error?
        self.performAndWait {
            
            do {
                
                count = try self.count(for: fetchRequest.staticCast())
            }
            catch {
                
                countError = error
            }
        }
        if count == NSNotFound {

            let coreStoreError = CoreStoreError(countError)
            Internals.log(
                coreStoreError,
                "Failed executing count request."
            )
            throw coreStoreError
        }
        return count
    }
    
    @nonobjc
    internal func fetchObjectID(_ fetchRequest: Internals.CoreStoreFetchRequest<NSManagedObjectID>) throws -> NSManagedObjectID? {
        
        var fetchResults: [NSManagedObjectID]?
        var fetchError: Error?
        self.performAndWait {
            
            do {
                
                fetchResults = try self.fetch(fetchRequest.staticCast())
            }
            catch {
                
                fetchError = error
            }
        }
        if let fetchResults = fetchResults {

            return fetchResults.first
        }
        let coreStoreError = CoreStoreError(fetchError)
        Internals.log(
            coreStoreError,
            "Failed executing fetch request."
        )
        throw coreStoreError
    }
    
    
    // MARK: Querying
    
    @nonobjc
    internal func queryValue<O, U: QueryableAttributeType>(_ selectTerms: [SelectTerm<O>], fetchRequest: Internals.CoreStoreFetchRequest<NSDictionary>) throws -> U? {
        
        var fetchResults: [Any]?
        var fetchError: Error?
        self.performAndWait {
            
            do {
                
                fetchResults = try self.fetch(fetchRequest.staticCast())
            }
            catch {
                
                fetchError = error
            }
        }
        if let fetchResults = fetchResults {
            
            if let rawResult = fetchResults.first as? NSDictionary,
                let rawObject = rawResult[selectTerms.first!.keyPathString] as? U.QueryableNativeType {
                
                return Select<O, U>.ReturnType.cs_fromQueryableNativeType(rawObject)
            }
            return nil
        }
        let coreStoreError = CoreStoreError(fetchError)
        Internals.log(
            coreStoreError,
            "Failed executing fetch request."
        )
        throw coreStoreError
    }
    
    @nonobjc
    internal func queryValue<O>(_ selectTerms: [SelectTerm<O>], fetchRequest: Internals.CoreStoreFetchRequest<NSDictionary>) throws -> Any? {
        
        var fetchResults: [Any]?
        var fetchError: Error?
        self.performAndWait {
            
            do {
                
                fetchResults = try self.fetch(fetchRequest.staticCast())
            }
            catch {
                
                fetchError = error
            }
        }
        if let fetchResults = fetchResults {
            
            if let rawResult = fetchResults.first as? NSDictionary,
                let rawObject = rawResult[selectTerms.first!.keyPathString] {
                
                return rawObject
            }
            return nil
        }
        let coreStoreError = CoreStoreError(fetchError)
        Internals.log(
            coreStoreError,
            "Failed executing fetch request."
        )
        throw coreStoreError
    }
    
    @nonobjc
    internal func queryAttributes(_ fetchRequest: Internals.CoreStoreFetchRequest<NSDictionary>) throws -> [[String: Any]] {
        
        var fetchResults: [Any]?
        var fetchError: Error?
        self.performAndWait {
            
            do {
                
                fetchResults = try self.fetch(fetchRequest.staticCast())
            }
            catch {
                
                fetchError = error
            }
        }
        if let fetchResults = fetchResults {
            
            return NSDictionary.cs_fromQueryResultsNativeType(fetchResults)
        }
        let coreStoreError = CoreStoreError(fetchError)
        Internals.log(
            coreStoreError,
            "Failed executing fetch request."
        )
        throw coreStoreError
    }
    
    
    // MARK: Deleting
    
    @nonobjc
    internal func deleteAll<O: NSManagedObject>(_ fetchRequest: Internals.CoreStoreFetchRequest<O>) throws -> Int {
        
        var numberOfDeletedObjects: Int?
        var fetchError: Error?
        self.performAndWait {
            
            autoreleasepool {
                
                do {
                    
                    let fetchResults = try self.fetch(fetchRequest.staticCast())
                    for object in fetchResults {
                        
                        self.delete(object)
                    }
                    numberOfDeletedObjects = fetchResults.count
                }
                catch {
                    
                    fetchError = error
                }
            }
        }
        if let numberOfDeletedObjects = numberOfDeletedObjects {

            return numberOfDeletedObjects
        }
        let coreStoreError = CoreStoreError(fetchError)
        Internals.log(
            coreStoreError,
            "Failed executing delete request."
        )
        throw coreStoreError
    }
}