package oidc

import (
	"context"
	"crypto/sha512"
	"hash"
	"html/template"
	"net/url"
	"time"

	"github.com/hashicorp/go-retryablehttp"
	"github.com/ory/fosite"
	"github.com/ory/fosite/handler/oauth2"
	"github.com/ory/fosite/handler/openid"
	"github.com/ory/fosite/handler/par"
	"github.com/ory/fosite/handler/pkce"
	"github.com/ory/fosite/i18n"
	"github.com/ory/fosite/token/hmac"
	"github.com/ory/fosite/token/jwt"

	"github.com/authelia/authelia/v4/internal/configuration/schema"
	"github.com/authelia/authelia/v4/internal/templates"
	"github.com/authelia/authelia/v4/internal/utils"
)

func NewConfig(config *schema.OpenIDConnect, templates *templates.Provider) (c *Config) {
	c = &Config{
		GlobalSecret:               []byte(utils.HashSHA256FromString(config.HMACSecret)),
		SendDebugMessagesToClients: config.EnableClientDebugMessages,
		MinParameterEntropy:        config.MinimumParameterEntropy,
		Lifespans: LifespanConfig{
			AccessToken:   config.AccessTokenLifespan,
			AuthorizeCode: config.AuthorizeCodeLifespan,
			IDToken:       config.IDTokenLifespan,
			RefreshToken:  config.RefreshTokenLifespan,
		},
		ProofKeyCodeExchange: ProofKeyCodeExchangeConfig{
			Enforce:                   config.EnforcePKCE == "always",
			EnforcePublicClients:      config.EnforcePKCE != "never",
			AllowPlainChallengeMethod: config.EnablePKCEPlainChallenge,
		},
		PAR: PARConfig{
			Enforced:        config.PAR.Enforce,
			ContextLifespan: config.PAR.ContextLifespan,
			URIPrefix:       RedirectURIPrefixPushedAuthorizationRequestURN,
		},
		Templates: templates,
	}

	c.Strategy.Core = &HMACCoreStrategy{
		Enigma: &hmac.HMACStrategy{Config: c},
		Config: c,
	}

	return c
}

// Config is an implementation of the fosite.Configurator.
type Config struct {
	// GlobalSecret is the global secret used to sign and verify signatures.
	GlobalSecret []byte

	// RotatedGlobalSecrets is a list of global secrets that are used to verify signatures.
	RotatedGlobalSecrets [][]byte

	Issuers IssuersConfig

	SendDebugMessagesToClients    bool
	DisableRefreshTokenValidation bool
	OmitRedirectScopeParameter    bool

	JWTScopeField  jwt.JWTScopeFieldEnum
	JWTMaxDuration time.Duration

	Hasher               *Hasher
	Hash                 HashConfig
	Strategy             StrategyConfig
	PAR                  PARConfig
	Handlers             HandlersConfig
	Lifespans            LifespanConfig
	ProofKeyCodeExchange ProofKeyCodeExchangeConfig
	GrantTypeJWTBearer   GrantTypeJWTBearerConfig

	TokenURL            string
	TokenEntropy        int
	MinParameterEntropy int

	SanitationWhiteList []string
	AllowedPrompts      []string
	RefreshTokenScopes  []string

	HTTPClient     *retryablehttp.Client
	MessageCatalog i18n.MessageCatalog

	Templates *templates.Provider
}

// HashConfig holds specific fosite.Configurator information for hashing.
type HashConfig struct {
	ClientSecrets fosite.Hasher
	HMAC          func() (h hash.Hash)
}

// StrategyConfig holds specific fosite.Configurator information for various strategies.
type StrategyConfig struct {
	Core                 oauth2.CoreStrategy
	OpenID               openid.OpenIDConnectTokenStrategy
	Audience             fosite.AudienceMatchingStrategy
	Scope                fosite.ScopeStrategy
	JWKSFetcher          fosite.JWKSFetcherStrategy
	ClientAuthentication fosite.ClientAuthenticationStrategy
}

// PARConfig holds specific fosite.Configurator information for Pushed Authorization Requests.
type PARConfig struct {
	Enforced        bool
	URIPrefix       string
	ContextLifespan time.Duration
}

// IssuersConfig holds specific fosite.Configurator information for the issuer.
type IssuersConfig struct {
	IDToken     string
	AccessToken string
}

// HandlersConfig holds specific fosite.Configurator handlers configuration information.
type HandlersConfig struct {
	// ResponseMode provides an extension handler for custom response modes.
	ResponseMode fosite.ResponseModeHandler

	// AuthorizeEndpoint is a list of handlers that are called before the authorization endpoint is served.
	AuthorizeEndpoint fosite.AuthorizeEndpointHandlers

	// TokenEndpoint is a list of handlers that are called before the token endpoint is served.
	TokenEndpoint fosite.TokenEndpointHandlers

	// TokenIntrospection is a list of handlers that are called before the token introspection endpoint is served.
	TokenIntrospection fosite.TokenIntrospectionHandlers

	// Revocation is a list of handlers that are called before the revocation endpoint is served.
	Revocation fosite.RevocationHandlers

	// PushedAuthorizeEndpoint is a list of handlers that are called before the PAR endpoint is served.
	PushedAuthorizeEndpoint fosite.PushedAuthorizeEndpointHandlers
}

// GrantTypeJWTBearerConfig holds specific fosite.Configurator information for the JWT Bearer Grant Type.
type GrantTypeJWTBearerConfig struct {
	OptionalClientAuth bool
	OptionalJTIClaim   bool
	OptionalIssuedDate bool
}

// ProofKeyCodeExchangeConfig holds specific fosite.Configurator information for PKCE.
type ProofKeyCodeExchangeConfig struct {
	Enforce                   bool
	EnforcePublicClients      bool
	AllowPlainChallengeMethod bool
}

// LifespanConfig holds specific fosite.Configurator information for various lifespans.
type LifespanConfig struct {
	AccessToken   time.Duration
	AuthorizeCode time.Duration
	IDToken       time.Duration
	RefreshToken  time.Duration
}

// LoadHandlers reloads the handlers based on the current configuration.
func (c *Config) LoadHandlers(store *Store, strategy jwt.Signer) {
	validator := openid.NewOpenIDConnectRequestValidator(strategy, c)

	handlers := []any{
		&oauth2.AuthorizeExplicitGrantHandler{
			AccessTokenStrategy:    c.Strategy.Core,
			RefreshTokenStrategy:   c.Strategy.Core,
			AuthorizeCodeStrategy:  c.Strategy.Core,
			CoreStorage:            store,
			TokenRevocationStorage: store,
			Config:                 c,
		},
		&oauth2.AuthorizeImplicitGrantTypeHandler{
			AccessTokenStrategy: c.Strategy.Core,
			AccessTokenStorage:  store,
			Config:              c,
		},
		&oauth2.ClientCredentialsGrantHandler{
			HandleHelper: &oauth2.HandleHelper{
				AccessTokenStrategy: c.Strategy.Core,
				AccessTokenStorage:  store,
				Config:              c,
			},
			Config: c,
		},
		&oauth2.RefreshTokenGrantHandler{
			AccessTokenStrategy:    c.Strategy.Core,
			RefreshTokenStrategy:   c.Strategy.Core,
			TokenRevocationStorage: store,
			Config:                 c,
		},
		&openid.OpenIDConnectExplicitHandler{
			IDTokenHandleHelper: &openid.IDTokenHandleHelper{
				IDTokenStrategy: c.Strategy.OpenID,
			},
			OpenIDConnectRequestValidator: validator,
			OpenIDConnectRequestStorage:   store,
			Config:                        c,
		},
		&openid.OpenIDConnectImplicitHandler{
			AuthorizeImplicitGrantTypeHandler: &oauth2.AuthorizeImplicitGrantTypeHandler{
				AccessTokenStrategy: c.Strategy.Core,
				AccessTokenStorage:  store,
				Config:              c,
			},
			IDTokenHandleHelper: &openid.IDTokenHandleHelper{
				IDTokenStrategy: c.Strategy.OpenID,
			},
			OpenIDConnectRequestValidator: validator,
			Config:                        c,
		},
		&openid.OpenIDConnectHybridHandler{
			AuthorizeExplicitGrantHandler: &oauth2.AuthorizeExplicitGrantHandler{
				AccessTokenStrategy:   c.Strategy.Core,
				RefreshTokenStrategy:  c.Strategy.Core,
				AuthorizeCodeStrategy: c.Strategy.Core,
				CoreStorage:           store,
				Config:                c,
			},
			Config: c,
			AuthorizeImplicitGrantTypeHandler: &oauth2.AuthorizeImplicitGrantTypeHandler{
				AccessTokenStrategy: c.Strategy.Core,
				AccessTokenStorage:  store,
				Config:              c,
			},
			IDTokenHandleHelper: &openid.IDTokenHandleHelper{
				IDTokenStrategy: c.Strategy.OpenID,
			},
			OpenIDConnectRequestValidator: validator,
			OpenIDConnectRequestStorage:   store,
		},
		&openid.OpenIDConnectRefreshHandler{
			IDTokenHandleHelper: &openid.IDTokenHandleHelper{
				IDTokenStrategy: c.Strategy.OpenID,
			},
			Config: c,
		},
		&oauth2.CoreValidator{
			CoreStrategy: c.Strategy.Core,
			CoreStorage:  store,
			Config:       c,
		},
		&oauth2.TokenRevocationHandler{
			AccessTokenStrategy:    c.Strategy.Core,
			RefreshTokenStrategy:   c.Strategy.Core,
			TokenRevocationStorage: store,
		},
		&pkce.Handler{
			AuthorizeCodeStrategy: c.Strategy.Core,
			Storage:               store,
			Config:                c,
		},
		&par.PushedAuthorizeHandler{
			Storage: store,
			Config:  c,
		},
	}

	x := HandlersConfig{}

	for _, handler := range handlers {
		if h, ok := handler.(fosite.AuthorizeEndpointHandler); ok {
			x.AuthorizeEndpoint.Append(h)
		}

		if h, ok := handler.(fosite.TokenEndpointHandler); ok {
			x.TokenEndpoint.Append(h)
		}

		if h, ok := handler.(fosite.TokenIntrospector); ok {
			x.TokenIntrospection.Append(h)
		}

		if h, ok := handler.(fosite.RevocationHandler); ok {
			x.Revocation.Append(h)
		}

		if h, ok := handler.(fosite.PushedAuthorizeEndpointHandler); ok {
			x.PushedAuthorizeEndpoint.Append(h)
		}
	}

	c.Handlers = x
}

// GetAllowedPrompts returns the allowed prompts.
func (c *Config) GetAllowedPrompts(ctx context.Context) (prompts []string) {
	if len(c.AllowedPrompts) == 0 {
		c.AllowedPrompts = []string{PromptNone, PromptLogin, PromptConsent}
	}

	return c.AllowedPrompts
}

// GetEnforcePKCE returns the enforcement of PKCE.
func (c *Config) GetEnforcePKCE(ctx context.Context) (enforce bool) {
	return c.ProofKeyCodeExchange.Enforce
}

// GetEnforcePKCEForPublicClients returns the enforcement of PKCE for public clients.
func (c *Config) GetEnforcePKCEForPublicClients(ctx context.Context) (enforce bool) {
	return c.GetEnforcePKCE(ctx) || c.ProofKeyCodeExchange.EnforcePublicClients
}

// GetEnablePKCEPlainChallengeMethod returns the enable PKCE plain challenge method.
func (c *Config) GetEnablePKCEPlainChallengeMethod(ctx context.Context) (enable bool) {
	return c.ProofKeyCodeExchange.AllowPlainChallengeMethod
}

// GetGrantTypeJWTBearerCanSkipClientAuth returns the grant type JWT bearer can skip client auth.
func (c *Config) GetGrantTypeJWTBearerCanSkipClientAuth(ctx context.Context) (skip bool) {
	return c.GrantTypeJWTBearer.OptionalClientAuth
}

// GetGrantTypeJWTBearerIDOptional returns the grant type JWT bearer ID optional.
func (c *Config) GetGrantTypeJWTBearerIDOptional(ctx context.Context) (optional bool) {
	return c.GrantTypeJWTBearer.OptionalJTIClaim
}

// GetGrantTypeJWTBearerIssuedDateOptional returns the grant type JWT bearer issued date optional.
func (c *Config) GetGrantTypeJWTBearerIssuedDateOptional(ctx context.Context) (optional bool) {
	return c.GrantTypeJWTBearer.OptionalIssuedDate
}

// GetJWTMaxDuration returns the JWT max duration.
func (c *Config) GetJWTMaxDuration(ctx context.Context) (duration time.Duration) {
	if c.JWTMaxDuration == 0 {
		c.JWTMaxDuration = time.Hour * 24
	}

	return c.JWTMaxDuration
}

// GetRedirectSecureChecker returns the redirect URL security validator.
func (c *Config) GetRedirectSecureChecker(ctx context.Context) func(context.Context, *url.URL) (secure bool) {
	return fosite.IsRedirectURISecure
}

// GetOmitRedirectScopeParam must be set to true if the scope query param is to be omitted
// in the authorization's redirect URI.
func (c *Config) GetOmitRedirectScopeParam(ctx context.Context) (omit bool) {
	return c.OmitRedirectScopeParameter
}

// GetSanitationWhiteList is a whitelist of form values that are required by the token endpoint. These values
// are safe for storage in a database (cleartext).
func (c *Config) GetSanitationWhiteList(ctx context.Context) (whitelist []string) {
	return c.SanitationWhiteList
}

// GetJWTScopeField returns the JWT scope field.
func (c *Config) GetJWTScopeField(ctx context.Context) (field jwt.JWTScopeFieldEnum) {
	if c.JWTScopeField == jwt.JWTScopeFieldUnset {
		c.JWTScopeField = jwt.JWTScopeFieldList
	}

	return c.JWTScopeField
}

// GetIDTokenIssuer returns the ID token issuer.
func (c *Config) GetIDTokenIssuer(ctx context.Context) (issuer string) {
	return c.Issuers.IDToken
}

// GetAccessTokenIssuer returns the access token issuer.
func (c *Config) GetAccessTokenIssuer(ctx context.Context) (issuer string) {
	return c.Issuers.AccessToken
}

// GetDisableRefreshTokenValidation returns the disable refresh token validation flag.
func (c *Config) GetDisableRefreshTokenValidation(ctx context.Context) (disable bool) {
	return c.DisableRefreshTokenValidation
}

// GetAuthorizeCodeLifespan returns the authorization code lifespan.
func (c *Config) GetAuthorizeCodeLifespan(ctx context.Context) (lifespan time.Duration) {
	if c.Lifespans.AuthorizeCode.Seconds() <= 0 {
		c.Lifespans.AuthorizeCode = lifespanAuthorizeCodeDefault
	}

	return c.Lifespans.AuthorizeCode
}

// GetRefreshTokenLifespan returns the refresh token lifespan.
func (c *Config) GetRefreshTokenLifespan(ctx context.Context) (lifespan time.Duration) {
	if c.Lifespans.RefreshToken.Seconds() <= 0 {
		c.Lifespans.RefreshToken = lifespanRefreshTokenDefault
	}

	return c.Lifespans.RefreshToken
}

// GetIDTokenLifespan returns the ID token lifespan.
func (c *Config) GetIDTokenLifespan(ctx context.Context) (lifespan time.Duration) {
	if c.Lifespans.IDToken.Seconds() <= 0 {
		c.Lifespans.IDToken = lifespanTokenDefault
	}

	return c.Lifespans.IDToken
}

// GetAccessTokenLifespan returns the access token lifespan.
func (c *Config) GetAccessTokenLifespan(ctx context.Context) (lifespan time.Duration) {
	if c.Lifespans.AccessToken.Seconds() <= 0 {
		c.Lifespans.AccessToken = lifespanTokenDefault
	}

	return c.Lifespans.AccessToken
}

// GetTokenEntropy returns the token entropy.
func (c *Config) GetTokenEntropy(ctx context.Context) (entropy int) {
	if c.TokenEntropy == 0 {
		c.TokenEntropy = 32
	}

	return c.TokenEntropy
}

// GetGlobalSecret returns the global secret.
func (c *Config) GetGlobalSecret(ctx context.Context) (secret []byte, err error) {
	return c.GlobalSecret, nil
}

// GetRotatedGlobalSecrets returns the rotated global secrets.
func (c *Config) GetRotatedGlobalSecrets(ctx context.Context) (secrets [][]byte, err error) {
	return c.RotatedGlobalSecrets, nil
}

// GetHTTPClient returns the HTTP client provider.
func (c *Config) GetHTTPClient(ctx context.Context) (client *retryablehttp.Client) {
	if c.HTTPClient == nil {
		c.HTTPClient = retryablehttp.NewClient()
	}

	return c.HTTPClient
}

// GetRefreshTokenScopes returns the refresh token scopes.
func (c *Config) GetRefreshTokenScopes(ctx context.Context) (scopes []string) {
	if c.RefreshTokenScopes == nil {
		c.RefreshTokenScopes = []string{ScopeOffline, ScopeOfflineAccess}
	}

	return c.RefreshTokenScopes
}

// GetScopeStrategy returns the scope strategy.
func (c *Config) GetScopeStrategy(ctx context.Context) (strategy fosite.ScopeStrategy) {
	if c.Strategy.Scope == nil {
		c.Strategy.Scope = fosite.ExactScopeStrategy
	}

	return c.Strategy.Scope
}

// GetAudienceStrategy returns the audience strategy.
func (c *Config) GetAudienceStrategy(ctx context.Context) (strategy fosite.AudienceMatchingStrategy) {
	if c.Strategy.Audience == nil {
		c.Strategy.Audience = fosite.DefaultAudienceMatchingStrategy
	}

	return c.Strategy.Audience
}

// GetMinParameterEntropy returns the minimum parameter entropy.
func (c *Config) GetMinParameterEntropy(_ context.Context) (entropy int) {
	if c.MinParameterEntropy == 0 {
		c.MinParameterEntropy = fosite.MinParameterEntropy
	}

	return c.MinParameterEntropy
}

// GetHMACHasher returns the hash function.
func (c *Config) GetHMACHasher(ctx context.Context) func() (h hash.Hash) {
	if c.Hash.HMAC == nil {
		c.Hash.HMAC = sha512.New512_256
	}

	return c.Hash.HMAC
}

// GetSendDebugMessagesToClients returns the send debug messages to clients.
func (c *Config) GetSendDebugMessagesToClients(ctx context.Context) (send bool) {
	return c.SendDebugMessagesToClients
}

// GetJWKSFetcherStrategy returns the JWKS fetcher strategy.
func (c *Config) GetJWKSFetcherStrategy(ctx context.Context) (strategy fosite.JWKSFetcherStrategy) {
	if c.Strategy.JWKSFetcher == nil {
		c.Strategy.JWKSFetcher = fosite.NewDefaultJWKSFetcherStrategy()
	}

	return c.Strategy.JWKSFetcher
}

// GetClientAuthenticationStrategy returns the client authentication strategy.
func (c *Config) GetClientAuthenticationStrategy(ctx context.Context) (strategy fosite.ClientAuthenticationStrategy) {
	return c.Strategy.ClientAuthentication
}

// GetMessageCatalog returns the message catalog.
func (c *Config) GetMessageCatalog(ctx context.Context) (catalog i18n.MessageCatalog) {
	return c.MessageCatalog
}

// GetFormPostHTMLTemplate returns the form post HTML template.
func (c *Config) GetFormPostHTMLTemplate(ctx context.Context) (tmpl *template.Template) {
	if c.Templates == nil {
		return nil
	}

	return c.Templates.GetOpenIDConnectAuthorizeResponseFormPostTemplate()
}

// GetTokenURL returns the token URL.
func (c *Config) GetTokenURL(ctx context.Context) (tokenURL string) {
	if octx, ok := ctx.(OpenIDConnectContext); ok {
		switch issuerURL, err := octx.IssuerURL(); err {
		case nil:
			return issuerURL.JoinPath(EndpointPathToken).String()
		default:
			return c.TokenURL
		}
	}

	return c.TokenURL
}

// GetSecretsHasher returns the client secrets hashing function.
func (c *Config) GetSecretsHasher(ctx context.Context) (hasher fosite.Hasher) {
	if c.Hash.ClientSecrets == nil {
		c.Hash.ClientSecrets, _ = NewHasher()
	}

	return c.Hash.ClientSecrets
}

// GetUseLegacyErrorFormat returns whether to use the legacy error format.
//
// Deprecated: Do not use this flag anymore.
func (c *Config) GetUseLegacyErrorFormat(ctx context.Context) (use bool) {
	return false
}

// GetAuthorizeEndpointHandlers returns the authorize endpoint handlers.
func (c *Config) GetAuthorizeEndpointHandlers(ctx context.Context) (handlers fosite.AuthorizeEndpointHandlers) {
	return c.Handlers.AuthorizeEndpoint
}

// GetTokenEndpointHandlers returns the token endpoint handlers.
func (c *Config) GetTokenEndpointHandlers(ctx context.Context) (handlers fosite.TokenEndpointHandlers) {
	return c.Handlers.TokenEndpoint
}

// GetTokenIntrospectionHandlers returns the token introspection handlers.
func (c *Config) GetTokenIntrospectionHandlers(ctx context.Context) (handlers fosite.TokenIntrospectionHandlers) {
	return c.Handlers.TokenIntrospection
}

// GetRevocationHandlers returns the revocation handlers.
func (c *Config) GetRevocationHandlers(ctx context.Context) (handlers fosite.RevocationHandlers) {
	return c.Handlers.Revocation
}

// GetPushedAuthorizeEndpointHandlers returns the handlers.
func (c *Config) GetPushedAuthorizeEndpointHandlers(ctx context.Context) fosite.PushedAuthorizeEndpointHandlers {
	return c.Handlers.PushedAuthorizeEndpoint
}

// GetResponseModeHandlerExtension returns the response mode handler extension.
func (c *Config) GetResponseModeHandlerExtension(ctx context.Context) (handler fosite.ResponseModeHandler) {
	return c.Handlers.ResponseMode
}

// GetPushedAuthorizeRequestURIPrefix is the request URI prefix. This is
// usually 'urn:ietf:params:oauth:request_uri:'.
func (c *Config) GetPushedAuthorizeRequestURIPrefix(ctx context.Context) string {
	if c.PAR.URIPrefix == "" {
		c.PAR.URIPrefix = RedirectURIPrefixPushedAuthorizationRequestURN
	}

	return c.PAR.URIPrefix
}

// EnforcePushedAuthorize indicates if PAR is enforced. In this mode, a client
// cannot pass authorize parameters at the 'authorize' endpoint. The 'authorize' endpoint
// must contain the PAR request_uri.
func (c *Config) EnforcePushedAuthorize(ctx context.Context) bool {
	return c.PAR.Enforced
}

// GetPushedAuthorizeContextLifespan is the lifespan of the short-lived PAR context.
func (c *Config) GetPushedAuthorizeContextLifespan(ctx context.Context) (lifespan time.Duration) {
	if c.PAR.ContextLifespan.Seconds() <= 0 {
		c.PAR.ContextLifespan = lifespanPARContextDefault
	}

	return c.PAR.ContextLifespan
}