// Vikunja is a to-do list application to facilitate your life.
// Copyright 2018-present Vikunja and contributors. All rights reserved.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

// Package humaecho5 is a Huma adapter for labstack/echo/v5, vendored from
// the unmerged upstream PR https://github.com/danielgtaylor/huma/pull/959
// until it lands (Huma's own humaecho is echo/v4 only). Delete and switch
// back to upstream once that PR merges.
//
// Vikunja-specific glue: every request stashes its *echo.Context on
// context.Context under EchoContextKey so handlers can reach the echo
// context via auth.GetAuthFromContext without per-handler wiring.
package humaecho5

import (
	"context"
	"crypto/tls"
	"io"
	"mime/multipart"
	"net/http"
	"net/url"
	"strings"
	"time"

	"github.com/danielgtaylor/huma/v2"
	"github.com/labstack/echo/v5"
)

// MultipartMaxMemory caps in-memory buffering for multipart form parsing.
var MultipartMaxMemory int64 = 8 * 1024

type echoContextKey struct{}

// EchoContextKey retrieves the underlying *echo.Context from a Huma
// handler's context.Context.
var EchoContextKey = echoContextKey{}

// Unwrap extracts the underlying Echo context from a Huma context. Panics if
// called on a context from a different adapter.
func Unwrap(ctx huma.Context) *echo.Context {
	for {
		if c, ok := ctx.(interface{ Unwrap() huma.Context }); ok {
			ctx = c.Unwrap()
			continue
		}
		break
	}
	if c, ok := ctx.(*echoCtx); ok {
		return c.Unwrap()
	}
	panic("not a humaecho5 context")
}

type echoCtx struct {
	op     *huma.Operation
	orig   *echo.Context
	status int
}

var _ huma.Context = &echoCtx{}

func (c *echoCtx) Unwrap() *echo.Context      { return c.orig }
func (c *echoCtx) Operation() *huma.Operation { return c.op }

func (c *echoCtx) Context() context.Context {
	// Stash echo context so auth.GetAuthFromContext can retrieve it.
	return context.WithValue((*c.orig).Request().Context(), EchoContextKey, c.orig)
}

func (c *echoCtx) Method() string     { return (*c.orig).Request().Method }
func (c *echoCtx) Host() string       { return (*c.orig).Request().Host }
func (c *echoCtx) RemoteAddr() string { return (*c.orig).Request().RemoteAddr }
func (c *echoCtx) URL() url.URL       { return *(*c.orig).Request().URL }

func (c *echoCtx) Param(name string) string  { return (*c.orig).Param(name) }
func (c *echoCtx) Query(name string) string  { return (*c.orig).QueryParam(name) }
func (c *echoCtx) Header(name string) string { return (*c.orig).Request().Header.Get(name) }

func (c *echoCtx) EachHeader(cb func(name, value string)) {
	for name, values := range (*c.orig).Request().Header {
		for _, value := range values {
			cb(name, value)
		}
	}
}

func (c *echoCtx) BodyReader() io.Reader { return (*c.orig).Request().Body }

func (c *echoCtx) GetMultipartForm() (*multipart.Form, error) {
	err := (*c.orig).Request().ParseMultipartForm(MultipartMaxMemory)
	return (*c.orig).Request().MultipartForm, err
}

func (c *echoCtx) SetReadDeadline(deadline time.Time) error {
	return huma.SetReadDeadline((*c.orig).Response(), deadline)
}

func (c *echoCtx) SetStatus(code int) {
	c.status = code
	(*c.orig).Response().WriteHeader(code)
}

func (c *echoCtx) Status() int { return c.status }

func (c *echoCtx) AppendHeader(name, value string) {
	(*c.orig).Response().Header().Add(name, value)
}

func (c *echoCtx) SetHeader(name, value string) {
	(*c.orig).Response().Header().Set(name, value)
}

func (c *echoCtx) BodyWriter() io.Writer { return (*c.orig).Response() }

func (c *echoCtx) TLS() *tls.ConnectionState { return (*c.orig).Request().TLS }

func (c *echoCtx) Version() huma.ProtoVersion {
	r := (*c.orig).Request()
	return huma.ProtoVersion{
		Proto:      r.Proto,
		ProtoMajor: r.ProtoMajor,
		ProtoMinor: r.ProtoMinor,
	}
}

type router interface {
	Add(method, path string, handler echo.HandlerFunc, middlewares ...echo.MiddlewareFunc) echo.RouteInfo
}

type echoAdapter struct {
	http.Handler
	router router
	// groupPrefix (e.g. "/api/v2") gets prepended to internal Huma
	// dispatches whose path doesn't already start with it — required so
	// autopatch's relative path resolution works under a sub-group.
	groupPrefix string
}

func (a *echoAdapter) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if a.groupPrefix != "" && !strings.HasPrefix(r.URL.Path, a.groupPrefix) {
		r = r.Clone(r.Context())
		r.URL.Path = a.groupPrefix + r.URL.Path
		if r.URL.RawPath != "" {
			r.URL.RawPath = a.groupPrefix + r.URL.RawPath
		}
	}
	a.Handler.ServeHTTP(w, r)
}

func (a *echoAdapter) Handle(op *huma.Operation, handler func(huma.Context)) {
	// Convert {param} to :param for Echo's router.
	path := op.Path
	path = strings.ReplaceAll(path, "{", ":")
	path = strings.ReplaceAll(path, "}", "")
	a.router.Add(op.Method, path, func(c *echo.Context) error {
		ctx := &echoCtx{op: op, orig: c}
		handler(ctx)
		return nil
	})
}

// New creates a new Huma API using the provided Echo router.
func New(r *echo.Echo, config huma.Config) huma.API {
	return huma.NewAPI(config, &echoAdapter{Handler: r, router: r})
}

// NewWithGroup mounts a Huma API on a group so handlers inherit its
// middleware. groupPrefix must equal the prefix g was constructed with;
// the adapter uses it to rewrite internal Huma dispatches (notably
// autopatch's GET+PUT round trip) onto absolute URLs.
func NewWithGroup(r *echo.Echo, g *echo.Group, groupPrefix string, config huma.Config) huma.API {
	return huma.NewAPI(config, &echoAdapter{Handler: r, router: g, groupPrefix: groupPrefix})
}