package main

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"

	"git.cin.su/m/Assistant/contracts/identity"
)

var (
	errCreatorSessionDenied = errors.New("creator session denied")
	errIdentityUnavailable  = errors.New("identity service unavailable")
)

type creatorIdentityClient struct {
	baseURL *url.URL
	client  *http.Client
}

func newCreatorIdentityClient(rawURL string, client *http.Client) (creatorIdentityClient, error) {
	baseURL, err := url.Parse(rawURL)
	if err != nil || baseURL.Scheme == "" || baseURL.Host == "" {
		return creatorIdentityClient{}, fmt.Errorf("invalid Core Runtime URL")
	}
	return creatorIdentityClient{baseURL: baseURL, client: client}, nil
}

func (c creatorIdentityClient) Session(ctx context.Context, authorization string) (identity.CreatorSession, error) {
	if !strings.HasPrefix(authorization, "Bearer ") || len(strings.TrimPrefix(authorization, "Bearer ")) == 0 {
		return identity.CreatorSession{}, errCreatorSessionDenied
	}
	target := *c.baseURL
	target.Path = "/v1/creator/sessions/current"
	target.RawQuery = ""
	request, err := http.NewRequestWithContext(ctx, http.MethodGet, target.String(), nil)
	if err != nil {
		return identity.CreatorSession{}, fmt.Errorf("%w: build request", errIdentityUnavailable)
	}
	request.Header.Set("Authorization", authorization)
	response, err := c.client.Do(request)
	if err != nil {
		return identity.CreatorSession{}, fmt.Errorf("%w: %v", errIdentityUnavailable, err)
	}
	defer response.Body.Close()
	if response.StatusCode == http.StatusUnauthorized {
		return identity.CreatorSession{}, errCreatorSessionDenied
	}
	if response.StatusCode != http.StatusOK {
		return identity.CreatorSession{}, fmt.Errorf("%w: status %d", errIdentityUnavailable, response.StatusCode)
	}
	var session identity.CreatorSession
	if err := json.NewDecoder(io.LimitReader(response.Body, 16<<10)).Decode(&session); err != nil {
		return identity.CreatorSession{}, fmt.Errorf("%w: invalid response", errIdentityUnavailable)
	}
	if session.ActorID == "" || session.PrincipalID == "" {
		return identity.CreatorSession{}, fmt.Errorf("%w: incomplete session", errIdentityUnavailable)
	}
	return session, nil
}