package httpx

import (
	"encoding/xml"
	"fmt"
	"net/http"

	apierrors "git.yuntuo.hk/k2safe/go-omni/errors"
	"git.yuntuo.hk/k2safe/go-omni/response"
)

// SetResponseEncoder overrides this request's success AND error encoding. A
// cloned context inherits it, including buffered/idempotent requests.
func (c *Context) SetResponseEncoder(encoder response.Encoder) { c.encoder = encoder }

// WithResponse applies a policy to one route/group. It deliberately stays set
// until the outer error boundary finishes handling this request.
func WithResponse(encoder response.Encoder) Middleware {
	return func(next Handler) Handler {
		return func(c *Context) error { c.SetResponseEncoder(encoder); return next(c) }
	}
}

// ResponseRegistrar installs the response policy before application middleware,
// so early auth/protection failures and buffered clones use the route contract.
type ResponseRegistrar interface {
	HandleWithResponse(string, string, response.Encoder, Handler, ...Middleware)
}

// HandleWithResponse uses the registrar's early policy hook when available.
// Custom registrars without this hook get an ordinary leading route middleware.
func HandleWithResponse(router interface {
	Handle(string, string, Handler, ...Middleware)
}, method, path string, encoder response.Encoder, handler Handler, middleware ...Middleware) {
	if r, ok := router.(ResponseRegistrar); ok {
		r.HandleWithResponse(method, path, encoder, handler, middleware...)
		return
	}
	all := append([]Middleware{WithResponse(encoder)}, middleware...)
	router.Handle(method, path, handler, all...)
}

func (c *Context) writeResult(result response.Result) (err error) {
	if c.responded {
		return nil
	}
	defer func() {
		if recovered := recover(); recovered != nil {
			err = apierrors.Internal(fmt.Errorf("response encoder panic: %v", recovered))
		}
	}()
	encoder := c.encoder
	if encoder == nil {
		encoder = response.Default()
	}
	payload, err := encoder.Encode(result)
	if err != nil {
		return apierrors.Internal(err)
	}
	if result.PreserveStatus {
		payload.Status = result.Status
	}
	if payload.Status < 200 || payload.Status > 599 {
		return apierrors.Internal(fmt.Errorf("response encoder returned invalid status %d", payload.Status))
	}
	if (payload.Status == 204 || payload.Status == 304) && len(payload.Body) > 0 {
		return apierrors.Internal(fmt.Errorf("response encoder returned a body for status %d", payload.Status))
	}
	return c.WriteResponse(payload.Status, payload.Header, payload.Body)
}

// RespondStatus uses the current response format and error catalog, but keeps
// the explicit HTTP status even if a catalog/custom encoder selects another.
// This is useful for protocol endpoints such as health probes. Ordinary
// business handlers should use OK/Created or return their error as usual.
func (c *Context) RespondStatus(status int, data any, err error) error {
	if c.Responded() {
		return nil
	}
	if status < 200 || status > 599 || status == 204 || status == 205 || status == 304 {
		return apierrors.Internal(fmt.Errorf("response requires a body-bearing HTTP status"))
	}
	result := response.Result{Status: status, Code: "OK", Message: "success", Data: data,
		RequestID: c.RequestID(), PreserveStatus: true}
	if err != nil {
		failure := c.ResolveError(err)
		failure.Status = status
		c.failure = failure
		result.Code, result.Message, result.BusinessCode = failure.Code, failure.Message, failure.BusinessCode
		result.Err, result.Failed = err, true
	}
	writeErr := c.writeResult(result)
	if writeErr != nil && !c.Responded() {
		// A broken encoder must not fall through to a business error policy
		// that acknowledges failures with HTTP 200. Commit a bodyless failure.
		failureStatus := status
		if failureStatus < 400 {
			failureStatus = http.StatusInternalServerError
		}
		c.failure = c.ResolveError(writeErr)
		c.failure.Status = failureStatus
		_ = c.WriteResponse(failureStatus, nil, nil)
	}
	return writeErr
}

// Bytes, Text and XML are explicit wire responses; they bypass any envelope.
func (c *Context) Bytes(status int, contentType string, body []byte) error {
	return c.WriteResponse(status, http.Header{"Content-Type": {contentType}}, body)
}
func (c *Context) Text(status int, body string) error {
	return c.Bytes(status, "text/plain; charset=utf-8", []byte(body))
}
func (c *Context) XML(status int, value any) error {
	if c.responded {
		return nil
	}
	body, err := xml.Marshal(value)
	if err != nil {
		return apierrors.Internal(err)
	}
	return c.Bytes(status, "application/xml; charset=utf-8", body)
}