package strings

import (
	"strings"

	"github.com/zclconf/go-cty/cty"
	"github.com/zclconf/go-cty/cty/function"
)

func Join() function.Function {
	return function.New(&function.Spec{
		Description: "join a list of strings",
		Params: []function.Parameter{
			{
				Name:        "separator",
				Description: "separator to be used to join the strings",
				Type:        cty.String,
			},
			{
				Name:        "list",
				Description: "list of strings to join",
				Type:        cty.List(cty.String),
			},
		},
		Type: function.StaticReturnType(cty.String),
		Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
			separator := args[0].AsString()
			rawElems := args[1].AsValueSlice()

			elems := make([]string, len(rawElems))
			for i := range rawElems {
				elems[i] = rawElems[i].AsString()
			}

			return cty.StringVal(strings.Join(elems, separator)), nil
		},
	})
}