package strings

import (
	"fmt"

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

func Format() function.Function {
	return function.New(&function.Spec{
		Description: "Format a string",
		Params: []function.Parameter{
			{
				Name:        "format",
				Description: "format for the resulting string",
				Type:        cty.String,
			},
		},
		VarParam: &function.Parameter{
			Name:        "args",
			Description: "variadic args for format",
			Type:        cty.DynamicPseudoType,
		},
		Type: function.StaticReturnType(cty.String),
		Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
			format := args[0].AsString()
			formatArgs := make([]any, 0, len(args))

			if len(args) > 1 {
				for i := 1; i < len(args); i++ {
					if unboxed := unbox(args[i]); unboxed != nil {
						formatArgs = append(formatArgs, unboxed)
					}
				}
			}

			return cty.StringVal(fmt.Sprintf(format, formatArgs...)), nil
		},
	})
}

func unbox(in cty.Value) any {
	switch in.Type() {
	case cty.String:
		return in.AsString()
	case cty.Number:
		bigFloat := in.AsBigFloat()
		if bigFloat.IsInt() {
			i, _ := bigFloat.Int64()
			return i
		} else {
			f, _ := bigFloat.Float64()
			return f
		}
	case cty.Bool:
		return in.True()
	default:
		return nil
	}
}