package param

import (
	"encoding"

	"github.com/gin-gonic/gin"

	"ruben/inventory2/server/response"
)

// Spec is the entry point of the package.
// It's typically constructed via Path() or Form().
// But it's zero value is valid.
//
// It's methods support a builder pattern to minimize API bloat.
//
// To complete gin parameter parsing, call Unmarshal().
type Spec struct {
	path map[string]encoding.TextUnmarshaler
	form map[string]encoding.TextUnmarshaler
}

func Path(k string, dst encoding.TextUnmarshaler) Spec {
	return Spec{
		path: map[string]encoding.TextUnmarshaler{
			k: dst,
		},
	}
}

func Form(k string, dst encoding.TextUnmarshaler) Spec {
	return Spec{
		form: map[string]encoding.TextUnmarshaler{
			k: dst,
		},
	}
}

func (s Spec) Path(k string, dst encoding.TextUnmarshaler) Spec {
	if s.path == nil {
		s.path = make(map[string]encoding.TextUnmarshaler, 1)
	}
	s.path[k] = dst
	return s
}

func (s Spec) Form(k string, dst encoding.TextUnmarshaler) Spec {
	if s.form == nil {
		s.form = make(map[string]encoding.TextUnmarshaler, 1)
	}
	s.form[k] = dst
	return s
}

func (s Spec) Unmarshal(c *gin.Context) error {
	for k, dst := range s.path {
		v := c.Param(k)
		if v == "" {
			return response.NotFound().Msgf("no %s provided", k)
		}
		if err := dst.UnmarshalText([]byte(v)); err != nil {
			return response.NotFound().Wrap(err).Msgf("invalid %s", k)
		}
	}
	for k, dst := range s.form {
		v, ok := c.GetPostForm(k)
		if !ok || v == "" {
			if v, ok = c.GetQuery(k); !ok {
				return response.BadRequest().Msgf("no %s provided", k)
			}
		}
		if err := dst.UnmarshalText([]byte(v)); err != nil {
			return response.BadRequest().Wrap(err).Msgf("invalid %s provided", k)
		}
	}

	return nil
}