package worker

import (

	"bytes"

	"context"

	"crypto/tls"

	"encoding/json"

	"fmt"

	"io"

	"net"

	"net/http"

	"net/url"

	"github.com/google/uuid"

	"github.com/osbuild/osbuild-composer/internal/common"

	"github.com/osbuild/osbuild-composer/internal/worker/api"

)

type Client struct {

	server    *url.URL

	requester *http.Client

}

type Job interface {

	Id() uuid.UUID

	Type() string

	Args(args interface{}) error

	DynamicArgs(i int, args interface{}) error

	NDynamicArgs() int

	Update(result interface{}) error

	Canceled() (bool, error)

	UploadArtifact(name string, reader io.Reader) error

}

type job struct {

	requester        *http.Client

	id               uuid.UUID

	location         string

	artifactLocation string

	jobType          string

	args             json.RawMessage

	dynamicArgs      []json.RawMessage

}

func NewClient(baseURL string, conf *tls.Config) (*Client, error) {

	server, err := url.Parse(baseURL)

	if err != nil {

		return nil, err

	}

	server, err = server.Parse(api.BasePath + "/")

	if err != nil {

		panic(err)

	}

	requester := &http.Client{

		Transport: &http.Transport{

			TLSClientConfig: conf,

		},

	}

	return &Client{server, requester}, nil

}

func NewClientUnix(path string) *Client {

	server, err := url.Parse("http://localhost/")

	if err != nil {

		panic(err)

	}

	server, err = server.Parse(api.BasePath + "/")

	if err != nil {

		panic(err)

	}

	requester := &http.Client{

		Transport: &http.Transport{

			DialContext: func(context context.Context, network, addr string) (net.Conn, error) {

				return net.Dial("unix", path)

			},

		},

	}

	return &Client{server, requester}

}

func (c *Client) RequestJob(types []string) (Job, error) {

	url, err := c.server.Parse("jobs")

	if err != nil {

		// This only happens when "jobs" cannot be parsed.

		panic(err)

	}

	var buf bytes.Buffer

	err = json.NewEncoder(&buf).Encode(api.RequestJobJSONRequestBody{

		Types: types,

		Arch:  common.CurrentArch(),

	})

	if err != nil {

		panic(err)

	}

	response, err := c.requester.Post(url.String(), "application/json", &buf)

	if err != nil {

		return nil, fmt.Errorf("error requesting job: %v", err)

	}

	defer response.Body.Close()

	if response.StatusCode != http.StatusCreated {

		return nil, errorFromResponse(response, "error requesting job")

	}

	var jr requestJobResponse

	err = json.NewDecoder(response.Body).Decode(&jr)

	if err != nil {

		return nil, fmt.Errorf("error parsing response: %v", err)

	}

	location, err := c.server.Parse(jr.Location)

	if err != nil {

		return nil, fmt.Errorf("error parsing location url in response: %v", err)

	}

	artifactLocation, err := c.server.Parse(jr.ArtifactLocation)

	if err != nil {

		return nil, fmt.Errorf("error parsing artifact location url in response: %v", err)

	}

	return &job{

		requester:        c.requester,

		id:               jr.Id,

		jobType:          jr.Type,

		args:             jr.Args,

		dynamicArgs:      jr.DynamicArgs,

		location:         location.String(),

		artifactLocation: artifactLocation.String(),

	}, nil

}

func (j *job) Id() uuid.UUID {

	return j.id

}

func (j *job) Type() string {

	return j.jobType

}

func (j *job) Args(args interface{}) error {

	err := json.Unmarshal(j.args, args)

	if err != nil {

		return fmt.Errorf("error parsing job arguments: %v", err)

	}

	return nil

}

func (j *job) NDynamicArgs() int {

	return len(j.dynamicArgs)

}

func (j *job) DynamicArgs(i int, args interface{}) error {

	err := json.Unmarshal(j.dynamicArgs[i], args)

	if err != nil {

		return fmt.Errorf("error parsing job arguments: %v", err)

	}

	return nil

}

func (j *job) Update(result interface{}) error {

	var buf bytes.Buffer

	err := json.NewEncoder(&buf).Encode(api.UpdateJobJSONRequestBody{

		Result: result,

	})

	if err != nil {

		panic(err)

	}

	req, err := http.NewRequest("PATCH", j.location, &buf)

	if err != nil {

		panic(err)

	}

	req.Header.Add("Content-Type", "application/json")

	response, err := j.requester.Do(req)

	if err != nil {

		return fmt.Errorf("error fetching job info: %v", err)

	}

	defer response.Body.Close()

	if response.StatusCode != http.StatusOK {

		return errorFromResponse(response, "error setting job status")

	}

	return nil

}

func (j *job) Canceled() (bool, error) {

	response, err := j.requester.Get(j.location)

	if err != nil {

		return false, fmt.Errorf("error fetching job info: %v", err)

	}

	defer response.Body.Close()

	if response.StatusCode != http.StatusOK {

		return false, errorFromResponse(response, "error fetching job info")

	}

	var jr getJobResponse

	err = json.NewDecoder(response.Body).Decode(&jr)

	if err != nil {

		return false, fmt.Errorf("error parsing reponse: %v", err)

	}

	return jr.Canceled, nil

}

func (j *job) UploadArtifact(name string, reader io.Reader) error {

	if j.artifactLocation == "" {

		return fmt.Errorf("server does not accept artifacts for this job")

	}

	loc, err := url.Parse(j.artifactLocation)

	if err != nil {

		return fmt.Errorf("error parsing job location: %v", err)

	}

	loc, err = loc.Parse(url.PathEscape(name))

	if err != nil {

		panic(err)

	}

	req, err := http.NewRequest("PUT", loc.String(), reader)

	if err != nil {

		return fmt.Errorf("cannot create request: %v", err)

	}

	req.Header.Add("Content-Type", "application/octet-stream")

	response, err := j.requester.Do(req)

	if err != nil {

		return fmt.Errorf("error uploading artifact: %v", err)

	}

	if response.StatusCode != 200 {

		return errorFromResponse(response, "error uploading artifact")

	}

	return nil

}

// Parses an api.Error from a response and returns it as a golang error. Other

// errors, such failing to parse the response, are returned as golang error as

// well. If client code expects an error, it gets one.

func errorFromResponse(response *http.Response, message string) error {

	var e api.Error

	err := json.NewDecoder(response.Body).Decode(&e)

	if err != nil {

		return fmt.Errorf("failed to parse error response: %v", err)

	}

	return fmt.Errorf("%v: %v — %v", message, response.StatusCode, e.Message)

}