package generator

import (
	"io"
	"strings"

	"github.com/dave/jennifer/jen"
	"go.elara.ws/go-lemmy/cmd/gen/extractor"
)

type RoutesGenerator struct {
	w       io.Writer
	PkgName string
}

func NewRoutes(w io.Writer, pkgName string) *RoutesGenerator {
	return &RoutesGenerator{w, pkgName}
}

func (r *RoutesGenerator) Generate(routes []extractor.Route) error {
	f := jen.NewFile(r.PkgName)
	f.HeaderComment("Code generated by go.elara.ws/go-lemmy/cmd/gen (routes generator). DO NOT EDIT.")

	for _, r := range routes {

		f.Comment(r.Summary)
		f.Func().Params(
			jen.Id("c").Id("*Client"),
		).Id(transformName(r.Name)).ParamsFunc(func(g *jen.Group) {
			g.Id("ctx").Qual("context", "Context")
			if r.ParamsName != "" {
				g.Id("data").Qual("go.elara.ws/go-lemmy/types", r.ParamsName)
			}
		}).ParamsFunc(func(g *jen.Group) {
			if r.ReturnName != "" {
				g.Op("*").Qual("go.elara.ws/go-lemmy/types", r.ReturnName)
			}
			g.Error()
		}).BlockFunc(func(g *jen.Group) {
			returnName := r.ReturnName
			if returnName == "" {
				returnName = "EmptyResponse"
			}

			if r.ParamsName == "" {
				g.Id("data").Op(":=").Qual("go.elara.ws/go-lemmy/types", "EmptyData").Block()
			}

			g.Id("resData").Op(":=").Op("&").Qual("go.elara.ws/go-lemmy/types", returnName).Block()

			var funcName string
			switch r.Method {
			case "GET":
				funcName = "getReq"
			default:
				funcName = "req"
			}

			g.List(jen.Id("res"), jen.Err()).Op(":=").Id("c").Dot(funcName).Params(
				jen.Id("ctx"), jen.Lit(r.Method), jen.Lit(r.Path), jen.Id("data"), jen.Op("&").Id("resData"),
			)
			g.If(jen.Err().Op("!=").Nil()).BlockFunc(func(g *jen.Group) {
				if returnName == "EmptyResponse" {
					g.Return(jen.Err())
				} else {
					g.Return(jen.Nil(), jen.Err())
				}
			})

			g.Err().Op("=").Id("resError").Params(jen.Id("res"), jen.Id("resData").Dot("LemmyResponse"))
			g.If(jen.Err().Op("!=").Nil()).BlockFunc(func(g *jen.Group) {
				if returnName == "EmptyResponse" {
					g.Return(jen.Err())
				} else {
					g.Return(jen.Nil(), jen.Err())
				}
			})

			if returnName == "EmptyResponse" {
				g.Return(jen.Nil())
			} else {
				g.Return(jen.Id("resData"), jen.Nil())
			}
		})
	}

	return f.Render(r.w)
}

func transformName(s string) string {
	s = strings.ToUpper(s[:1]) + s[1:]
	s = strings.TrimPrefix(s, "Get")
	s = strings.TrimPrefix(s, "List")
	return s
}