/*
 * Copyright 2017 Baidu, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the
 * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific language governing permissions
 * and limitations under the License.
 */

// builder.go - defines the RequestBuilder structure for BCE servies

package bce

import (
	"encoding/json"
	"fmt"
)

// RequestBuilder holds config data for bce request.
// Some of fields are required and the others are optional.
// The builder pattern can simplify the execution of requests.
type RequestBuilder struct {
	client Client

	url         string            // required
	method      string            // required
	queryParams map[string]string // optional
	headers     map[string]string // optional
	body        interface{}       // optional
	result      interface{}       // optional
}

// create RequestBuilder with the client.
func NewRequestBuilder(client Client) *RequestBuilder {
	return &RequestBuilder{
		client: client,
	}
}

func (b *RequestBuilder) WithURL(url string) *RequestBuilder {
	b.url = url
	return b
}

func (b *RequestBuilder) WithMethod(method string) *RequestBuilder {
	b.method = method
	return b
}

// set query param with the key/value directly.
func (b *RequestBuilder) WithQueryParam(key, value string) *RequestBuilder {
	if b.queryParams == nil {
		b.queryParams = make(map[string]string)
	}
	b.queryParams[key] = value
	return b
}

// set query param with the key/value only when the value is not blank.
func (b *RequestBuilder) WithQueryParamFilter(key, value string) *RequestBuilder {
	if len(value) == 0 {
		return b
	}
	return b.WithQueryParam(key, value)
}

func (b *RequestBuilder) WithQueryParams(params map[string]string) *RequestBuilder {
	if b.queryParams == nil {
		b.queryParams = params
	} else {
		for key, value := range params {
			b.queryParams[key] = value
		}
	}
	return b
}

func (b *RequestBuilder) WithHeader(key, value string) *RequestBuilder {
	if b.headers == nil {
		b.headers = make(map[string]string)
	}
	b.headers[key] = value
	return b
}

func (b *RequestBuilder) WithHeaders(headers map[string]string) *RequestBuilder {
	if b.headers == nil {
		b.headers = headers
	} else {
		for key, value := range headers {
			b.headers[key] = value
		}
	}
	return b
}

func (b *RequestBuilder) WithBody(body interface{}) *RequestBuilder {
	b.body = body
	return b
}

func (b *RequestBuilder) WithResult(result interface{}) *RequestBuilder {
	b.result = result
	return b
}

// Do will send request to bce and get result with the builder's parameters.
func (b *RequestBuilder) Do() error {
	if err := b.validate(); err != nil {
		return err
	}

	// build BceRequest
	req, err := b.buildBceRequest()
	if err != nil {
		return err
	}

	// get result from BceResponse
	if err := b.buildBceResponse(req); err != nil {
		return err
	}

	return nil
}

// Validate if the required fields are providered.
func (b *RequestBuilder) validate() error {
	if len(b.url) == 0 {
		return fmt.Errorf("The url can't be null.")
	}
	if len(b.method) == 0 {
		return fmt.Errorf("The method can't be null.")
	}
	if b.client == nil {
		return fmt.Errorf("The client can't be null.")
	}
	return nil
}

func (b *RequestBuilder) buildBceRequest() (*BceRequest, error) {
	// Build the request
	req := &BceRequest{}
	req.SetUri(b.url)
	req.SetMethod(b.method)

	if b.headers != nil {
		req.SetHeaders(b.headers)
	}
	if b.queryParams != nil {
		req.SetParams(b.queryParams)
	}
	if b.body != nil {
		bodyBytes, err := json.Marshal(b.body)
		if err != nil {
			return nil, err
		}
		body, err := NewBodyFromBytes(bodyBytes)
		if err != nil {
			return nil, err
		}
		req.SetBody(body)
	}

	return req, nil
}

func (b *RequestBuilder) buildBceResponse(req *BceRequest) error {
	// Send request and get response
	resp := &BceResponse{}
	if err := b.client.SendRequest(req, resp); err != nil {
		return err
	}
	if resp.IsFail() {
		return resp.ServiceError()
	}
	defer resp.Body().Close()

	if b.result == nil {
		return nil
	}

	return resp.ParseJsonBody(b.result)
}