//
//  KBNetworkManager.m
//  CustomKeyboard
//

#import "KBNetworkManager.h"

NSErrorDomain const KBNetworkErrorDomain = @"com.company.keyboard.network";

@interface KBNetworkManager ()
@property (nonatomic, strong) NSURLSession *session; // 懒创建，ephemeral 配置
// 私有错误派发
- (void)fail:(KBNetworkError)code completion:(KBNetworkCompletion)completion;
@end

@implementation KBNetworkManager

+ (instancetype)shared {
    static KBNetworkManager *m; static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ m = [KBNetworkManager new]; });
    return m;
}

- (instancetype)init {
    if (self = [super init]) {
        _enabled = NO; // 键盘扩展默认无网络能力，需外部显式开启
        _timeout = 10.0;
        _defaultHeaders = @{ @"Accept": @"application/json" };
    }
    return self;
}

#pragma mark - Public

- (NSURLSessionDataTask *)GET:(NSString *)path
                     parameters:(NSDictionary *)parameters
                        headers:(NSDictionary<NSString *,NSString *> *)headers
                      completion:(KBNetworkCompletion)completion {
    if (![self ensureEnabled:completion]) return nil;
    NSURL *url = [self buildURLWithPath:path params:parameters];
    if (!url) { [self fail:KBNetworkErrorInvalidURL completion:completion]; return nil; }
    NSMutableURLRequest *req = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:self.timeout];
    req.HTTPMethod = @"GET";
    [self applyHeaders:headers toRequest:req contentType:nil];
    return [self startTaskWithRequest:req completion:completion];
}

- (NSURLSessionDataTask *)POST:(NSString *)path
                       jsonBody:(id)jsonBody
                        headers:(NSDictionary<NSString *,NSString *> *)headers
                      completion:(KBNetworkCompletion)completion {
    if (![self ensureEnabled:completion]) return nil;
    NSURL *url = [self buildURLWithPath:path params:nil];
    if (!url) { [self fail:KBNetworkErrorInvalidURL completion:completion]; return nil; }
    NSMutableURLRequest *req = [NSMutableURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:self.timeout];
    req.HTTPMethod = @"POST";
    NSData *body = nil;
    if (jsonBody) {
        if ([NSJSONSerialization isValidJSONObject:jsonBody]) {
            body = [NSJSONSerialization dataWithJSONObject:jsonBody options:0 error:NULL];
        } else if ([jsonBody isKindOfClass:[NSData class]]) {
            body = (NSData *)jsonBody; // 允许直接传入 NSData
        }
    }
    if (body) req.HTTPBody = body;
    [self applyHeaders:headers toRequest:req contentType:(body ? @"application/json" : nil)];
    return [self startTaskWithRequest:req completion:completion];
}

#pragma mark - Core

- (BOOL)ensureEnabled:(KBNetworkCompletion)completion {
    if (!self.isEnabled) {
        NSError *e = [NSError errorWithDomain:KBNetworkErrorDomain code:KBNetworkErrorDisabled userInfo:@{NSLocalizedDescriptionKey: @"网络未启用（可能未开启完全访问）"}];
        if (completion) completion(nil, nil, e);
        return NO;
    }
    return YES;
}

- (NSURL *)buildURLWithPath:(NSString *)path params:(NSDictionary *)params {
    NSURL *url = nil;
    if (path.length == 0) return nil;
    if ([path hasPrefix:@"http://"] || [path hasPrefix:@"https://"]) {
        url = [NSURL URLWithString:path];
    } else if (self.baseURL) {
        url = [NSURL URLWithString:path relativeToURL:self.baseURL].absoluteURL;
    }
    if (!url) return nil;
    if (params.count == 0) return url;
    NSURLComponents *c = [NSURLComponents componentsWithURL:url resolvingAgainstBaseURL:YES];
    NSMutableArray<NSURLQueryItem *> *items = c.queryItems.mutableCopy ?: [NSMutableArray array];
    [params enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
        NSString *k = [key description];
        NSString *v = [obj isKindOfClass:[NSString class]] ? obj : [obj description];
        [items addObject:[NSURLQueryItem queryItemWithName:k value:v]];
    }];
    c.queryItems = items;
    return c.URL;
}

- (void)applyHeaders:(NSDictionary<NSString *,NSString *> *)headers toRequest:(NSMutableURLRequest *)req contentType:(NSString *)contentType {
    // 合并默认头与局部头，局部覆盖
    NSMutableDictionary *all = [self.defaultHeaders mutableCopy] ?: [NSMutableDictionary new];
    if (contentType) all[@"Content-Type"] = contentType;
    [headers enumerateKeysAndObjectsUsingBlock:^(NSString *key, NSString *obj, BOOL *stop) { all[key] = obj; }];
    [all enumerateKeysAndObjectsUsingBlock:^(NSString *key, NSString *obj, BOOL *stop) { [req setValue:obj forHTTPHeaderField:key]; }];
}

- (NSURLSessionDataTask *)startTaskWithRequest:(NSURLRequest *)req completion:(KBNetworkCompletion)completion {
    NSURLSessionDataTask *task = [self.session dataTaskWithRequest:req
                                                completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        if (error) { if (completion) completion(nil, response, error); return; }
        if (!data) { if (completion) completion(nil, response, [NSError errorWithDomain:KBNetworkErrorDomain code:KBNetworkErrorInvalidResponse userInfo:@{NSLocalizedDescriptionKey:@"空响应"}]); return; }
        id json = nil;
        // 简单判断是否为 JSON
        NSString *ct = nil;
        if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
            ct = ((NSHTTPURLResponse *)response).allHeaderFields[@"Content-Type"];
        }
        BOOL looksJSON = (ct && [ct.lowercaseString containsString:@"application/json"]);
        if (looksJSON) {
            json = [NSJSONSerialization JSONObjectWithData:data options:0 error:&error];
            if (!json && completion) {
                completion(nil, response, [NSError errorWithDomain:KBNetworkErrorDomain code:KBNetworkErrorDecodeFailed userInfo:@{NSLocalizedDescriptionKey:@"JSON解析失败"}]);
                return;
            }
            if (completion) completion(json, response, nil);
        } else {
            if (completion) completion(data, response, nil);
        }
    }];
    [task resume];
    return task;
}

#pragma mark - Session

- (NSURLSession *)session {
    if (!_session) {
        NSURLSessionConfiguration *cfg = [NSURLSessionConfiguration ephemeralSessionConfiguration];
        cfg.requestCachePolicy = NSURLRequestReloadIgnoringLocalCacheData;
        cfg.timeoutIntervalForRequest = self.timeout;
        cfg.timeoutIntervalForResource = MAX(self.timeout, 30.0);
        if (@available(iOS 11.0, *)) { cfg.waitsForConnectivity = YES; }
        _session = [NSURLSession sessionWithConfiguration:cfg delegate:nil delegateQueue:nil];
    }
    return _session;
}

#pragma mark - Private helpers

- (void)fail:(KBNetworkError)code completion:(KBNetworkCompletion)completion {
    NSString *msg = @"网络错误";
    switch (code) {
        case KBNetworkErrorDisabled: msg = @"网络未启用（可能未开启完全访问）"; break;
        case KBNetworkErrorInvalidURL: msg = @"无效的URL"; break;
        case KBNetworkErrorInvalidResponse: msg = @"无效的响应"; break;
        case KBNetworkErrorDecodeFailed: msg = @"解析失败"; break;
        default: break;
    }
    NSError *e = [NSError errorWithDomain:KBNetworkErrorDomain
                                     code:code
                                 userInfo:@{NSLocalizedDescriptionKey: msg}];
    if (completion) completion(nil, nil, e);
}

@end