package web

import (
	"errors"
	"io"
	"net/http"

	"git.akyoto.dev/go/router"
)

// Context represents the interface for a request & response context.
type Context interface {
	Copy(io.Reader) error
	Bytes([]byte) error
	Error(...any) error
	File(string) error
	Get(string) string
	Next() error
	Redirect(int, string) error
	Request() Request
	Response() Response
	Status(int) Context
	String(string) error
}

// ctx represents a request & response context.
type ctx struct {
	request      request
	response     response
	server       *server
	params       []router.Parameter
	handlerCount uint8
}

// Bytes responds with a raw byte slice.
func (ctx *ctx) Bytes(body []byte) error {
	_, err := ctx.response.Write(body)
	return err
}

// Copy sends the contents of the io.Reader without creating an in-memory copy.
func (ctx *ctx) Copy(reader io.Reader) error {
	_, err := io.Copy(ctx.response.ResponseWriter, reader)
	return err
}

// Error is used for sending error messages to the client.
func (ctx *ctx) Error(messages ...any) error {
	var combined []error

	for _, msg := range messages {
		switch err := msg.(type) {
		case error:
			combined = append(combined, err)
		case string:
			combined = append(combined, errors.New(err))
		}
	}

	return errors.Join(combined...)
}

// Get retrieves a parameter.
func (ctx *ctx) Get(param string) string {
	for i := range len(ctx.params) {
		p := ctx.params[i]

		if p.Key == param {
			return p.Value
		}
	}

	return ""
}

// File serves the file at the given path.
func (ctx *ctx) File(path string) error {
	http.ServeFile(ctx.response.ResponseWriter, ctx.request.Request, path)
	return nil
}

// Next executes the next handler in the middleware chain.
func (ctx *ctx) Next() error {
	ctx.handlerCount++
	return ctx.server.handlers[ctx.handlerCount](ctx)
}

// Request returns the HTTP request.
func (ctx *ctx) Request() Request {
	return &ctx.request
}

// Response returns the HTTP response.
func (ctx *ctx) Response() Response {
	return &ctx.response
}

// Redirect sets the Location header and writes the headers with the given status code.
func (ctx *ctx) Redirect(code int, url string) error {
	ctx.Response().SetHeader("Location", url)
	ctx.Status(code)
	return nil
}

// Status sets the HTTP status of the response.
func (ctx *ctx) Status(status int) Context {
	ctx.response.WriteHeader(status)
	return ctx
}

// String responds with the given string.
func (ctx *ctx) String(body string) error {
	_, err := ctx.response.WriteString(body)
	return err
}

// addParameter adds a new parameter to the context.
func (ctx *ctx) addParameter(key string, value string) {
	ctx.params = append(ctx.params, router.Parameter{
		Key:   key,
		Value: value,
	})
}