package grafana

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"net/url"
	"path"
	"strings"

	"github.com/tidbcloud/tiinf/monitor/tilog"
	"go.uber.org/zap"
)

// DefaultHTTPClient initialized Grafana with appropriate conditions.
// It allows you globally redefine HTTP client.
var DefaultHTTPClient = http.DefaultClient

// Client uses Grafana REST API for interacting with Grafana server.
type Client struct {
	baseURL   string
	key       string
	basicAuth bool
	client    *http.Client
}

// StatusMessage reflects status message as it returned by Grafana REST API.
type StatusMessage struct {
	ID      *uint   `json:"id"`
	OrgID   *uint   `json:"orgId"`
	Message *string `json:"message"`
	Slug    *string `json:"slug"`
	Version *int    `json:"version"`
	Status  *string `json:"status"`
	UID     *string `json:"uid"`
	URL     *string `json:"url"`
}

// NewClient initializes client for interacting with an instance of Grafana server;
// apiKeyOrBasicAuth accepts either 'username:password' basic authentication credentials,
// or a Grafana API key
func NewClient(apiURL, apiKeyOrBasicAuth string, client *http.Client) *Client {
	key := ""
	basicAuth := strings.Contains(apiKeyOrBasicAuth, ":")
	baseURL, _ := url.Parse(apiURL)
	if !basicAuth {
		key = fmt.Sprintf("Bearer %s", apiKeyOrBasicAuth)
	} else {
		parts := strings.Split(apiKeyOrBasicAuth, ":")
		baseURL.User = url.UserPassword(parts[0], parts[1])
	}
	return &Client{baseURL: baseURL.String(), basicAuth: basicAuth, key: key, client: client}
}

func (r *Client) get(ctx context.Context, query string, params url.Values) ([]byte, int, error) {
	return r.doRequest(ctx, "GET", query, params, nil)
}

func (r *Client) patch(ctx context.Context, query string, params url.Values, body []byte) ([]byte, int, error) {
	return r.doRequest(ctx, "PATCH", query, params, bytes.NewBuffer(body))
}

func (r *Client) put(ctx context.Context, query string, params url.Values, body []byte) ([]byte, int, error) {
	return r.doRequest(ctx, "PUT", query, params, bytes.NewBuffer(body))
}

func (r *Client) post(ctx context.Context, query string, params url.Values, body []byte) ([]byte, int, error) {
	return r.doRequest(ctx, "POST", query, params, bytes.NewBuffer(body))
}

func (r *Client) delete(ctx context.Context, query string) ([]byte, int, error) {
	return r.doRequest(ctx, "DELETE", query, nil, nil)
}

func (r *Client) doRequest(ctx context.Context, method, query string, params url.Values, buf io.Reader) ([]byte, int, error) {
	u, _ := url.Parse(r.baseURL)
	u.Path = path.Join(u.Path, query)
	if params != nil {
		u.RawQuery = params.Encode()
	}
	req, err := http.NewRequest(method, u.String(), buf)
	if err != nil {
		return nil, 0, err
	}
	req = req.WithContext(ctx)
	if !r.basicAuth {
		req.Header.Set("Authorization", r.key)
	}
	req.Header.Set("Accept", "application/json")
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("User-Agent", "autograf")
	resp, err := r.client.Do(req)
	if err != nil {
		return nil, 0, err
	}
	data, err := ioutil.ReadAll(resp.Body)
	defer deferClose(resp.Body)
	return data, resp.StatusCode, err
}

func deferClose(c io.Closer) {
	if err := c.Close(); err != nil {
		tilog.Error(context.Background(), "failed to close", zap.Error(err))
	}
}