// Copyright 2022 Harness Inc. All rights reserved.
// Use of this source code is governed by the Polyform Free Trial License
// that can be found in the LICENSE.md file for this repository.

package client

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/http/httputil"
	"net/url"

	"github.com/rs/zerolog/log"

	"github.com/harness/gitness/types"
	"github.com/harness/gitness/version"
)

// ensure HTTPClient implements Client interface.
var _ Client = (*HTTPClient)(nil)

// HTTPClient provides an HTTP client for interacting
// with the remote API.
type HTTPClient struct {
	client *http.Client
	base   string
	token  string
	debug  bool
}

// New returns a client at the specified url.
func New(uri string) *HTTPClient {
	return NewToken(uri, "")
}

// NewToken returns a client at the specified url that
// authenticates all outbound requests with the given token.
func NewToken(uri, token string) *HTTPClient {
	return &HTTPClient{http.DefaultClient, uri, token, false}
}

// SetClient sets the default http client. This can be
// used in conjunction with golang.org/x/oauth2 to
// authenticate requests to the server.
func (c *HTTPClient) SetClient(client *http.Client) {
	c.client = client
}

// SetDebug sets the debug flag. When the debug flag is
// true, the http.Resposne body to stdout which can be
// helpful when debugging.
func (c *HTTPClient) SetDebug(debug bool) {
	c.debug = debug
}

// Login authenticates the user and returns a JWT token.
func (c *HTTPClient) Login(ctx context.Context, username, password string) (*types.TokenResponse, error) {
	form := &url.Values{}
	form.Add("username", username)
	form.Add("password", password)
	out := new(types.TokenResponse)
	uri := fmt.Sprintf("%s/api/v1/login", c.base)
	err := c.post(ctx, uri, form, out)
	return out, err
}

// Register registers a new  user and returns a JWT token.
func (c *HTTPClient) Register(ctx context.Context,
	username, name, email, password string) (*types.TokenResponse, error) {
	form := &url.Values{}
	form.Add("username", username)
	form.Add("name", name)
	form.Add("email", email)
	form.Add("password", password)
	out := new(types.TokenResponse)
	uri := fmt.Sprintf("%s/api/v1/register", c.base)
	err := c.post(ctx, uri, form, out)
	return out, err
}

//
// User Endpoints
//

// Self returns the currently authenticated user.
func (c *HTTPClient) Self(ctx context.Context) (*types.User, error) {
	out := new(types.User)
	uri := fmt.Sprintf("%s/api/v1/user", c.base)
	err := c.get(ctx, uri, out)
	return out, err
}

// User returns a user by ID or email.
func (c *HTTPClient) User(ctx context.Context, key string) (*types.User, error) {
	out := new(types.User)
	uri := fmt.Sprintf("%s/api/v1/users/%s", c.base, key)
	err := c.get(ctx, uri, out)
	return out, err
}

// UserList returns a list of all registered users.
func (c *HTTPClient) UserList(ctx context.Context, params types.Params) ([]types.User, error) {
	out := []types.User{}
	uri := fmt.Sprintf("%s/api/v1/users?page=%d&per_page=%d", c.base, params.Page, params.Size)
	err := c.get(ctx, uri, &out)
	return out, err
}

// UserCreate creates a new user account.
func (c *HTTPClient) UserCreate(ctx context.Context, user *types.User) (*types.User, error) {
	out := new(types.User)
	uri := fmt.Sprintf("%s/api/v1/users", c.base)
	err := c.post(ctx, uri, user, out)
	return out, err
}

// UserUpdate updates a user account by ID or email.
func (c *HTTPClient) UserUpdate(ctx context.Context, key string, user *types.UserInput) (*types.User, error) {
	out := new(types.User)
	uri := fmt.Sprintf("%s/api/v1/users/%s", c.base, key)
	err := c.patch(ctx, uri, user, out)
	return out, err
}

// UserDelete deletes a user account by ID or email.
func (c *HTTPClient) UserDelete(ctx context.Context, key string) error {
	uri := fmt.Sprintf("%s/api/v1/users/%s", c.base, key)
	err := c.delete(ctx, uri)
	return err
}

//
// http request helper functions
//

// helper function for making an http GET request.
func (c *HTTPClient) get(ctx context.Context, rawurl string, out interface{}) error {
	return c.do(ctx, rawurl, "GET", nil, out)
}

// helper function for making an http POST request.
func (c *HTTPClient) post(ctx context.Context, rawurl string, in, out interface{}) error {
	return c.do(ctx, rawurl, "POST", in, out)
}

// helper function for making an http PATCH request.
func (c *HTTPClient) patch(ctx context.Context, rawurl string, in, out interface{}) error {
	return c.do(ctx, rawurl, "PATCH", in, out)
}

// helper function for making an http DELETE request.
func (c *HTTPClient) delete(ctx context.Context, rawurl string) error {
	return c.do(ctx, rawurl, "DELETE", nil, nil)
}

// helper function to make an http request.
func (c *HTTPClient) do(ctx context.Context, rawurl, method string, in, out interface{}) error {
	// executes the http request and returns the body as
	// and io.ReadCloser
	body, err := c.stream(ctx, rawurl, method, in, out)
	if body != nil {
		defer func(body io.ReadCloser) {
			_ = body.Close()
		}(body)
	}
	if err != nil {
		return err
	}

	// if a json response is expected, parse and return
	// the json response.
	if out != nil {
		return json.NewDecoder(body).Decode(out)
	}
	return nil
}

// helper function to stream a http request.
func (c *HTTPClient) stream(ctx context.Context, rawurl, method string, in, _ interface{}) (io.ReadCloser, error) {
	uri, err := url.Parse(rawurl)
	if err != nil {
		return nil, err
	}

	// if we are posting or putting data, we need to
	// write it to the body of the request.
	var buf io.ReadWriter
	if in != nil {
		buf = &bytes.Buffer{}
		// if posting form data, encode the form values.
		if form, ok := in.(*url.Values); ok {
			if _, err = io.WriteString(buf, form.Encode()); err != nil {
				log.Err(err).Msg("in stream method")
			}
		} else if err = json.NewEncoder(buf).Encode(in); err != nil {
			return nil, err
		}
	}

	// creates a new http request.
	req, err := http.NewRequestWithContext(ctx, method, uri.String(), buf)
	if err != nil {
		return nil, err
	}
	if in != nil {
		req.Header.Set("Content-Type", "application/json")
	}
	if c.token != "" {
		req.Header.Set("Authorization", "Bearer "+c.token)
	}
	if _, ok := in.(*url.Values); ok {
		req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	}

	// include the client version information in the
	// http accept header for debugging purposes.
	req.Header.Set("Accept", "application/json;version="+version.Version.String())

	// send the http request.
	resp, err := c.client.Do(req)
	if err != nil {
		return nil, err
	}
	if c.debug {
		dump, _ := httputil.DumpResponse(resp, true)
		log.Debug().Msgf("method %s, url %s", method, rawurl)
		log.Debug().Msg(string(dump))
	}
	if resp.StatusCode >= http.StatusMultipleChoices {
		defer func(Body io.ReadCloser) {
			_ = Body.Close()
		}(resp.Body)
		err = &remoteError{}
		if decodeErr := json.NewDecoder(resp.Body).Decode(err); decodeErr != nil {
			return nil, decodeErr
		}
		return nil, err
	}
	return resp.Body, nil
}