package server

import (
	"net/http"

	"github.com/rancher/steve/pkg/schemaserver/handlers"
	"github.com/rancher/steve/pkg/schemaserver/parse"
	"github.com/rancher/steve/pkg/schemaserver/types"
	"github.com/rancher/steve/pkg/schemaserver/writer"
	"github.com/rancher/wrangler/pkg/merr"
	"github.com/rancher/wrangler/pkg/schemas/validation"
)

type RequestHandler interface {
	http.Handler

	GetSchemas() *types.APISchemas
	Handle(apiOp *types.APIRequest)
}

type Server struct {
	ResponseWriters  map[string]types.ResponseWriter
	Schemas          *types.APISchemas
	Defaults         Defaults
	AccessControl    types.AccessControl
	Parser           parse.Parser
	URLParser        parse.URLParser
}

type Defaults struct {
	ByIDHandler   types.RequestHandler
	ListHandler   types.RequestListHandler
	CreateHandler types.RequestHandler
	DeleteHandler types.RequestHandler
	UpdateHandler types.RequestHandler
	Store         types.Store
	ErrorHandler  types.ErrorHandler
}

func DefaultAPIServer() *Server {
	s := &Server{
		Schemas:          types.EmptyAPISchemas(),
		ResponseWriters: map[string]types.ResponseWriter{
			"json": &writer.EncodingResponseWriter{
				ContentType: "application/json",
				Encoder:     types.JSONEncoder,
			},
			"html": &writer.HTMLResponseWriter{
				EncodingResponseWriter: writer.EncodingResponseWriter{
					Encoder:     types.JSONEncoder,
					ContentType: "application/json",
				},
			},
			"yaml": &writer.EncodingResponseWriter{
				ContentType: "application/yaml",
				Encoder:     types.YAMLEncoder,
			},
		},
		AccessControl: &AllAccess{},
		Defaults: Defaults{
			ByIDHandler:   handlers.ByIDHandler,
			CreateHandler: handlers.CreateHandler,
			DeleteHandler: handlers.DeleteHandler,
			UpdateHandler: handlers.UpdateHandler,
			ListHandler:   handlers.ListHandler,
			ErrorHandler:  handlers.ErrorHandler,
		},
		Parser:    parse.Parse,
		URLParser: parse.MuxURLParser,
	}

	return s
}

func (s *Server) setDefaults(ctx *types.APIRequest) {
	if ctx.ResponseWriter == nil {
		ctx.ResponseWriter = s.ResponseWriters[ctx.ResponseFormat]
		if ctx.ResponseWriter == nil {
			ctx.ResponseWriter = s.ResponseWriters["json"]
		}
	}

	ctx.AccessControl = s.AccessControl

	if ctx.Schemas == nil {
		ctx.Schemas = s.Schemas
	}
}

func (s *Server) AddSchemas(schemas *types.APISchemas) error {
	var errs []error

	for _, schema := range schemas.Schemas {
		if err := s.addSchema(*schema); err != nil {
			errs = append(errs, err)
		}
	}

	return merr.NewErrors(errs...)
}

func (s *Server) addSchema(schema types.APISchema) error {
	s.setupDefaults(&schema)
	return s.Schemas.AddSchema(schema)
}

func (s *Server) setupDefaults(schema *types.APISchema) {
	if schema.Store == nil {
		schema.Store = s.Defaults.Store
	}

	if schema.ListHandler == nil {
		schema.ListHandler = s.Defaults.ListHandler
	}

	if schema.CreateHandler == nil {
		schema.CreateHandler = s.Defaults.CreateHandler
	}

	if schema.ByIDHandler == nil {
		schema.ByIDHandler = s.Defaults.ByIDHandler
	}

	if schema.UpdateHandler == nil {
		schema.UpdateHandler = s.Defaults.UpdateHandler
	}

	if schema.DeleteHandler == nil {
		schema.DeleteHandler = s.Defaults.DeleteHandler
	}

	if schema.ErrorHandler == nil {
		schema.ErrorHandler = s.Defaults.ErrorHandler
	}
}

func (s *Server) GetSchemas() *types.APISchemas {
	return s.Schemas
}

func (s *Server) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
	s.Handle(&types.APIRequest{
		Request:    req,
		Response:   rw,
	})
}

func (s *Server) Handle(apiOp *types.APIRequest) {
	s.handle(apiOp, s.Parser)
}

func (s *Server) handle(apiOp *types.APIRequest, parser parse.Parser) {
	if err := parser(apiOp, parse.MuxURLParser); err != nil {
		// ensure defaults set so writer is assigned
		s.setDefaults(apiOp)
		s.handleError(apiOp, err)
		return
	}

	s.setDefaults(apiOp)

	if code, data, err := s.handleOp(apiOp); err != nil {
		s.handleError(apiOp, err)
	} else if obj, ok := data.(types.APIObject); ok {
		apiOp.WriteResponse(code, obj)
	} else if list, ok := data.(types.APIObjectList); ok {
		apiOp.WriteResponseList(code, list)
	}
}

func (s *Server) handleOp(apiOp *types.APIRequest) (int, interface{}, error) {
	if err := CheckCSRF(apiOp); err != nil {
		return 0, nil, err
	}

	action, err := ValidateAction(apiOp)
	if err != nil {
		return 0, nil, err
	}

	if apiOp.Schema == nil {
		return http.StatusNotFound, nil, nil
	}

	if action != nil {
		return http.StatusOK, nil, handleAction(apiOp)
	}

	switch apiOp.Method {
	case http.MethodGet:
		if apiOp.Name == "" {
			data, err := handleList(apiOp, apiOp.Schema.ListHandler, s.Defaults.ListHandler)
			return http.StatusOK, data, err
		}
		data, err := handle(apiOp, apiOp.Schema.ByIDHandler, s.Defaults.ByIDHandler)
		return http.StatusOK, data, err
	case http.MethodPatch:
		fallthrough
	case http.MethodPut:
		data, err := handle(apiOp, apiOp.Schema.UpdateHandler, s.Defaults.UpdateHandler)
		return http.StatusOK, data, err
	case http.MethodPost:
		data, err := handle(apiOp, apiOp.Schema.CreateHandler, s.Defaults.CreateHandler)
		return http.StatusCreated, data, err
	case http.MethodDelete:
		data, err := handle(apiOp, apiOp.Schema.DeleteHandler, s.Defaults.DeleteHandler)
		return http.StatusOK, data, err
	}

	return http.StatusNotFound, nil, nil
}

func handleList(apiOp *types.APIRequest, custom types.RequestListHandler, handler types.RequestListHandler) (types.APIObjectList, error) {
	if custom != nil {
		return custom(apiOp)
	}
	return handler(apiOp)
}

func handle(apiOp *types.APIRequest, custom types.RequestHandler, handler types.RequestHandler) (types.APIObject, error) {
	if custom != nil {
		return custom(apiOp)
	}
	return handler(apiOp)
}

func handleAction(context *types.APIRequest) error {
	if err := context.AccessControl.CanAction(context, context.Schema, context.Action); err != nil {
		return err
	}
	if handler, ok := context.Schema.ActionHandlers[context.Action]; ok {
		handler.ServeHTTP(context.Response, context.Request)
		return validation.ErrComplete
	}
	return nil
}

func (s *Server) handleError(apiOp *types.APIRequest, err error) {
	if apiOp.Schema != nil && apiOp.Schema.ErrorHandler != nil {
		apiOp.Schema.ErrorHandler(apiOp, err)
	} else if s.Defaults.ErrorHandler != nil {
		s.Defaults.ErrorHandler(apiOp, err)
	}
}

func (s *Server) CustomAPIUIResponseWriter(cssURL, jsURL, version writer.StringGetter) {
	wi, ok := s.ResponseWriters["html"]
	if !ok {
		return
	}
	w, ok := wi.(*writer.HTMLResponseWriter)
	if !ok {
		return
	}
	w.CSSURL = cssURL
	w.JSURL = jsURL
	w.APIUIVersion = version
}