package execution

import (
	"bytes"
	"context"
	"encoding/json"
	"io"
	"net/http"
	"time"

	"github.com/zitadel/logging"

	"github.com/zitadel/zitadel/internal/api/authz"
	zhttp "github.com/zitadel/zitadel/internal/api/http"
	"github.com/zitadel/zitadel/internal/crypto"
	"github.com/zitadel/zitadel/internal/domain"
	target_domain "github.com/zitadel/zitadel/internal/execution/target"
	"github.com/zitadel/zitadel/internal/repository/execution"
	"github.com/zitadel/zitadel/internal/telemetry/tracing"
	"github.com/zitadel/zitadel/internal/zerrors"
	"github.com/zitadel/zitadel/pkg/actions"
)

type ContextInfo interface {
	GetHTTPRequestBody() []byte
	GetContent() interface{}
	SetHTTPResponseBody([]byte) error
}

// CallTargets call a list of targets in order with handling of error and responses
func CallTargets(
	ctx context.Context,
	targets []target_domain.Target,
	info ContextInfo,
	alg crypto.EncryptionAlgorithm,
) (_ interface{}, err error) {
	ctx, span := tracing.NewSpan(ctx)
	defer func() { span.EndWithError(err) }()

	for _, target := range targets {
		// call the type of target
		resp, err := CallTarget(ctx, target, info, alg)
		// handle error if interrupt is set
		if err != nil && target.IsInterruptOnError() {
			return nil, err
		}
		if len(resp) > 0 {
			// error in unmarshalling
			if err := info.SetHTTPResponseBody(resp); err != nil && target.IsInterruptOnError() {
				return nil, err
			}
		}
	}
	return info.GetContent(), nil
}

type ContextInfoRequest interface {
	GetHTTPRequestBody() []byte
}

// CallTarget call the desired type of target with handling of responses
func CallTarget(
	ctx context.Context,
	target target_domain.Target,
	info ContextInfoRequest,
	alg crypto.EncryptionAlgorithm,
) (res []byte, err error) {
	ctx, span := tracing.NewSpan(ctx)
	defer func() { span.EndWithError(err) }()

	signingKey, err := target.GetSigningKey(alg)
	if err != nil {
		return nil, zerrors.ThrowInternal(err, "EXEC-thiiCh5b", "Errors.Internal")
	}

	switch target.GetTargetType() {
	// get request, ignore response and return request and error for handling in list of targets
	case target_domain.TargetTypeWebhook:
		return nil, webhook(ctx, target.GetEndpoint(), target.GetTimeout(), info.GetHTTPRequestBody(), signingKey)
	// get request, return response and error
	case target_domain.TargetTypeCall:
		return Call(ctx, target.GetEndpoint(), target.GetTimeout(), info.GetHTTPRequestBody(), signingKey)
	case target_domain.TargetTypeAsync:
		go func(ctx context.Context, target target_domain.Target, info []byte) {
			if _, err := Call(ctx, target.GetEndpoint(), target.GetTimeout(), info, signingKey); err != nil {
				logging.WithFields("target", target.GetTargetID()).OnError(err).Info(err)
			}
		}(context.WithoutCancel(ctx), target, info.GetHTTPRequestBody())
		return nil, nil
	default:
		return nil, zerrors.ThrowInternal(nil, "EXEC-auqnansr2m", "Errors.Execution.Unknown")
	}
}

// webhook call a webhook, ignore the response but return the errror
func webhook(ctx context.Context, url string, timeout time.Duration, body []byte, signingKey string) error {
	_, err := Call(ctx, url, timeout, body, signingKey)
	return err
}

// Call function to do a post HTTP request to a desired url with timeout
func Call(ctx context.Context, url string, timeout time.Duration, body []byte, signingKey string) (_ []byte, err error) {
	ctx, cancel := context.WithTimeout(ctx, timeout)
	ctx, span := tracing.NewSpan(ctx)
	defer func() {
		cancel()
		span.EndWithError(err)
	}()

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewBuffer(body))
	if err != nil {
		return nil, err
	}
	req.Header.Set("Content-Type", "application/json")
	if signingKey != "" {
		req.Header.Set(actions.SigningHeader, actions.ComputeSignatureHeader(time.Now(), body, signingKey))
	}

	client := http.DefaultClient
	resp, err := client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	return HandleResponse(resp)
}

func HandleResponse(resp *http.Response) ([]byte, error) {
	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	// Check for success between 200 and 299, redirect 300 to 399 is handled by the client, return error with statusCode >= 400
	if resp.StatusCode >= 200 && resp.StatusCode <= 299 {
		var errorBody ErrorBody
		if err := json.Unmarshal(data, &errorBody); err != nil {
			// if json unmarshal fails, body has no ErrorBody information, so will be taken as successful response
			return data, nil
		}
		if errorBody.ForwardedStatusCode != 0 || errorBody.ForwardedErrorMessage != "" {
			if errorBody.ForwardedStatusCode >= 400 && errorBody.ForwardedStatusCode < 500 {
				return nil, zhttp.HTTPStatusCodeToZitadelError(nil, errorBody.ForwardedStatusCode, "EXEC-reUaUZCzCp", errorBody.ForwardedErrorMessage)
			}
			return nil, zerrors.ThrowPreconditionFailed(nil, "EXEC-bmhNhpcqpF", errorBody.ForwardedErrorMessage)
		}
		// no ErrorBody filled in response, so will be taken as successful response
		return data, nil
	}

	return nil, zerrors.ThrowPreconditionFailed(nil, "EXEC-dra6yamk98", "Errors.Execution.Failed")
}

type ErrorBody struct {
	ForwardedStatusCode   int    `json:"forwardedStatusCode,omitempty"`
	ForwardedErrorMessage string `json:"forwardedErrorMessage,omitempty"`
}

func QueryExecutionTargetsForRequest(
	ctx context.Context,
	fullMethod string,
) []target_domain.Target {
	ctx, span := tracing.NewSpan(ctx)
	defer span.End()

	requestTargets, _ := authz.GetInstance(ctx).ExecutionRouter().GetEventBestMatch(execution.ID(domain.ExecutionTypeRequest, fullMethod))
	return requestTargets
}

func QueryExecutionTargetsForResponse(
	ctx context.Context,
	fullMethod string,
) []target_domain.Target {
	ctx, span := tracing.NewSpan(ctx)
	defer span.End()

	responseTargets, _ := authz.GetInstance(ctx).ExecutionRouter().GetEventBestMatch(execution.ID(domain.ExecutionTypeResponse, fullMethod))
	return responseTargets
}

func QueryExecutionTargetsForFunction(ctx context.Context, function string) []target_domain.Target {
	executionTargets, _ := authz.GetInstance(ctx).ExecutionRouter().GetEventBestMatch(function)
	return executionTargets
}