// Copyright (c) 2026 Probo Inc <hello@probo.com>.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

package connector

import (
	"context"
	"encoding/base64"
	"encoding/json"
	"net/http"

	"go.gearno.de/kit/httpclient"
)

type APIKeyConnection struct {
	APIKey string `json:"api_key"`
	// Header selects how the API key is presented on outbound requests.
	// Empty (the default) sends it as `Authorization: Bearer <key>`,
	// which every OAuth-style and standard API-key connector uses. A
	// non-empty value (e.g. "x-api-key") sends the raw key in that
	// request header instead and omits Authorization entirely —
	// required by providers such as Anthropic that reject Bearer auth
	// and return 400 when both x-api-key and Authorization are present.
	// It is populated from the provider Registration at connector
	// creation time.
	Header string `json:"header,omitempty"`
	// BasicAuth, when true, presents the API key as the username of an
	// HTTP Basic credential with an empty password (`Authorization:
	// Basic base64(<key>:)`) — required by providers such as Cursor
	// whose Admin API documents Basic auth and rejects Bearer tokens.
	// It is mutually exclusive with Header and is populated from the
	// provider Registration at connector creation time.
	BasicAuth bool `json:"basic_auth,omitempty"`
	// BasicAuthUserPass, when true, presents the API key as a complete HTTP
	// Basic credential (`Authorization: Basic base64(<key>)`), with the
	// stored key already holding the `username:password` pair — required
	// by providers such as ClickHouse Cloud (keyId:keySecret) and
	// Langfuse (publicKey:secretKey) whose Basic credential carries a real
	// password, which BasicAuth (empty password) cannot express. It is
	// mutually exclusive with the other modes and is populated from the
	// provider Registration at connector creation time.
	BasicAuthUserPass bool `json:"basic_auth_user_pass,omitempty"`
	// Scheme selects a non-Bearer Authorization scheme: when non-empty
	// the key is sent as `Authorization: <Scheme> <key>` instead of
	// `Authorization: Bearer <key>` — required by providers such as Okta
	// whose API tokens use the `SSWS` scheme. It is mutually exclusive
	// with Header and BasicAuth and is populated from the provider
	// Registration at connector creation time.
	Scheme string `json:"scheme,omitempty"`
}

var _ Connection = (*APIKeyConnection)(nil)

func (c *APIKeyConnection) Type() ProtocolType {
	return ProtocolAPIKey
}

func (c *APIKeyConnection) Scopes() []string {
	return nil
}

func (c *APIKeyConnection) Client(ctx context.Context) (*http.Client, error) {
	underlying := httpclient.DefaultPooledTransport(httpclient.WithSSRFProtection())

	if c.BasicAuth {
		return &http.Client{
			Transport: &basicAuthTransport{
				username:   c.APIKey,
				underlying: underlying,
			},
		}, nil
	}

	if c.BasicAuthUserPass {
		return &http.Client{
			Transport: &basicAuthUserPassTransport{
				credential: c.APIKey,
				underlying: underlying,
			},
		}, nil
	}

	if c.Header != "" {
		return &http.Client{
			Transport: &apiKeyHeaderTransport{
				header:     c.Header,
				value:      c.APIKey,
				underlying: underlying,
			},
		}, nil
	}

	if c.Scheme != "" {
		return &http.Client{
			Transport: &schemeAuthTransport{
				scheme:     c.Scheme,
				token:      c.APIKey,
				underlying: underlying,
			},
		}, nil
	}

	return &http.Client{
		Transport: &oauth2Transport{
			token:      c.APIKey,
			tokenType:  "Bearer",
			underlying: underlying,
		},
	}, nil
}

// schemeAuthTransport presents the API key in the Authorization header
// under a non-Bearer scheme (`Authorization: <scheme> <token>`).
// Providers such as Okta document the `SSWS` scheme for their API tokens
// and reject Bearer, so neither oauth2Transport (which hardcodes Bearer)
// nor apiKeyHeaderTransport (which sets a non-Authorization header) fits.
type schemeAuthTransport struct {
	scheme     string
	token      string
	underlying http.RoundTripper
}

func (t *schemeAuthTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	req2 := req.Clone(req.Context())
	req2.Header.Set("Authorization", t.scheme+" "+t.token)

	return t.underlying.RoundTrip(req2)
}

// apiKeyHeaderTransport injects the API key into a custom request header
// (for example "x-api-key") and, unlike oauth2Transport, never sets
// Authorization. Providers such as Anthropic require the key in their
// own header and reject requests that carry both that header and
// Authorization.
type apiKeyHeaderTransport struct {
	header     string
	value      string
	underlying http.RoundTripper
}

func (t *apiKeyHeaderTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	req2 := req.Clone(req.Context())
	req2.Header.Set(t.header, t.value)

	return t.underlying.RoundTrip(req2)
}

// basicAuthTransport presents the API key as the username of an HTTP
// Basic credential with an empty password. Providers such as Cursor
// document `-u <key>:` Basic auth for their Admin API and reject Bearer
// tokens, so neither oauth2Transport nor apiKeyHeaderTransport fits.
type basicAuthTransport struct {
	username   string
	underlying http.RoundTripper
}

func (t *basicAuthTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	req2 := req.Clone(req.Context())
	req2.SetBasicAuth(t.username, "")

	return t.underlying.RoundTrip(req2)
}

// basicAuthUserPassTransport presents a complete HTTP Basic credential whose
// `username:password` pair is already encoded in the stored key
// (`Authorization: Basic base64(<credential>)`). Providers such as
// ClickHouse Cloud (keyId:keySecret) and Langfuse (publicKey:secretKey)
// authenticate with a real password, which basicAuthTransport's empty
// password cannot carry; SetBasicAuth would also re-append a ":" and
// corrupt the credential, so the value is base64-encoded verbatim.
type basicAuthUserPassTransport struct {
	credential string
	underlying http.RoundTripper
}

func (t *basicAuthUserPassTransport) RoundTrip(req *http.Request) (*http.Response, error) {
	req2 := req.Clone(req.Context())
	req2.Header.Set("Authorization", "Basic "+base64.StdEncoding.EncodeToString([]byte(t.credential)))

	return t.underlying.RoundTrip(req2)
}

func (c APIKeyConnection) MarshalJSON() ([]byte, error) {
	type Alias APIKeyConnection

	return json.Marshal(&struct {
		Type string `json:"type"`
		Alias
	}{
		Type:  string(ProtocolAPIKey),
		Alias: Alias(c),
	})
}

func (c *APIKeyConnection) UnmarshalJSON(data []byte) error {
	type Alias APIKeyConnection

	aux := &struct {
		*Alias
	}{
		Alias: (*Alias)(c),
	}

	return json.Unmarshal(data, &aux)
}