package core

import (
	"encoding/binary"

	"git.urbach.dev/cli/q/src/errors"
	"git.urbach.dev/cli/q/src/eval"
	"git.urbach.dev/cli/q/src/token"
	"git.urbach.dev/cli/q/src/types"
)

// EvaluateToken evaluates a single token.
func (f *Function) EvaluateToken(t token.Token) (eval.Value, error) {
	switch t.Kind {
	case token.Identifier:
		name := t.Text(f.File.Bytes)

		if name == "true" {
			value := &eval.Number{
				Typ:    types.Bool,
				Number: 1,
			}

			return value, nil
		}

		if name == "false" {
			value := &eval.Number{
				Typ:    types.Bool,
				Number: 0,
			}

			return value, nil
		}

		variable, function := f.Identifier(name)

		if variable != nil {
			f.UseVariable(variable)
			return &variable.Value, nil
		}

		if function != nil {
			value := &eval.Label{
				Typ:   types.AnyPointer,
				Label: function.UniqueName,
			}

			return value, nil
		}

		return nil, errors.New(&errors.UnknownIdentifier{Name: name}, f.File, t.Position)

	case token.Number, token.Rune:
		number, err := f.ToNumber(t)

		if err != nil {
			return nil, err
		}

		value := &eval.Number{
			Typ:    types.AnyInt,
			Number: number,
		}

		return value, nil

	case token.String:
		data := t.Bytes(f.File.Bytes)
		data = String(data)

		slice := make([]byte, len(data)+8+1)
		binary.LittleEndian.PutUint64(slice, uint64(len(data)))
		copy(slice[8:], data)
		label := f.AddBytes(slice)

		value := &eval.Label{
			Typ:   types.String,
			Label: label,
		}

		return value, nil
	}

	return nil, errors.New(errors.InvalidExpression, f.File, t.Position)
}