// Copyright © 2023 Ory Corp
// SPDX-License-Identifier: Apache-2.0

package oidc

import (
	"cmp"
	"context"
	"encoding/json"
	"net/url"
	"path"

	"github.com/hashicorp/go-retryablehttp"

	"github.com/ory/x/httpx"

	"github.com/pkg/errors"
	"golang.org/x/oauth2"

	"github.com/ory/herodot"
)

const (
	defaultEndpoint = "https://gitlab.com"
)

var _ OAuth2Provider = (*ProviderGitLab)(nil)

type ProviderGitLab struct {
	*ProviderGenericOIDC
}

func NewProviderGitLab(
	config *Configuration,
	reg Dependencies,
) Provider {
	return &ProviderGitLab{
		ProviderGenericOIDC: &ProviderGenericOIDC{
			config: config,
			reg:    reg,
		},
	}
}

func (g *ProviderGitLab) oauth2(ctx context.Context) (*oauth2.Config, error) {
	endpoint, err := g.endpoint()
	if err != nil {
		return nil, errors.WithStack(herodot.ErrInternalServerError().WithWrap(err).WithReasonf("%s", err))
	}

	authURL := *endpoint
	tokenURL := *endpoint

	authURL.Path = path.Join(authURL.Path, "/oauth/authorize")
	tokenURL.Path = path.Join(tokenURL.Path, "/oauth/token")

	return &oauth2.Config{
		ClientID:     g.config.ClientID,
		ClientSecret: g.config.ClientSecret,
		Endpoint: oauth2.Endpoint{
			AuthURL:  authURL.String(),
			TokenURL: tokenURL.String(),
		},
		Scopes:      g.config.Scope,
		RedirectURL: g.config.Redir(g.reg.Config().OIDCRedirectURIBase(ctx)),
	}, nil
}

func (g *ProviderGitLab) OAuth2(ctx context.Context) (*oauth2.Config, error) {
	return g.oauth2(ctx)
}

func (g *ProviderGitLab) Claims(ctx context.Context, exchange *oauth2.Token, query url.Values) (*Claims, error) {
	o, err := g.OAuth2(ctx)
	if err != nil {
		return nil, err
	}

	u, err := g.endpoint()
	if err != nil {
		return nil, errors.WithStack(herodot.ErrInternalServerError().WithWrap(err).WithReasonf("%s", err))
	}
	u.Path = path.Join(u.Path, "/oauth/userinfo")

	ctx, client := httpx.SetOAuth2(ctx, g.reg.HTTPClient(ctx), o, exchange)
	req, err := retryablehttp.NewRequestWithContext(ctx, "GET", u.String(), nil)
	if err != nil {
		return nil, errors.WithStack(herodot.ErrInternalServerError().WithWrap(err).WithReasonf("%s", err))
	}

	req.Header.Set("Accept", "application/json")
	resp, err := client.Do(req)
	if err != nil {
		return nil, errors.WithStack(herodot.ErrUpstreamError().WithWrap(err).WithReasonf("%s", err))
	}
	defer func() { _ = resp.Body.Close() }()

	if err := logUpstreamError(g.reg.Logger(), resp); err != nil {
		return nil, err
	}

	var claims Claims
	if err := json.NewDecoder(resp.Body).Decode(&claims); err != nil {
		return nil, errors.WithStack(herodot.ErrUpstreamError().WithWrap(err).WithReasonf("%s", err))
	}

	claims.Issuer = cmp.Or(claims.Issuer, g.config.IssuerURL)
	return &claims, nil
}

func (g *ProviderGitLab) endpoint() (*url.URL, error) {
	e := defaultEndpoint
	if len(g.config.IssuerURL) > 0 {
		e = g.config.IssuerURL
	}
	return url.Parse(e)
}