package core

import (
	"git.urbach.dev/cli/q/src/errors"
	"git.urbach.dev/cli/q/src/expression"
	"git.urbach.dev/cli/q/src/linter"
	"git.urbach.dev/cli/q/src/ssa"
	"git.urbach.dev/cli/q/src/token"
	"git.urbach.dev/cli/q/src/types"
)

// evaluateSlice converts a slice expression to an SSA value.
func (f *Function) evaluateSlice(expr *expression.Expression, index *expression.Expression, address ssa.Value, length ssa.Value) (ssa.Value, error) {
	if f.Env.Build.LintSlices {
		err := linter.LintSlice(expr, index, f.File)

		if err != nil {
			return nil, err
		}
	}

	switch len(index.Children) {
	case 1:
		from, err := f.evaluateRight(index.Children[0])

		if err != nil {
			return nil, err
		}

		if !types.Is(from.Type(), types.AnyInt) {
			return nil, errors.New(&TypeMismatch{Encountered: from.Type().Name(), Expected: types.AnyInt.Name()}, f.File, index.Children[0].Source())
		}

		return f.makeSlice(address, from, length, expr.Source()), nil
	case 2:
		if index.Children[0].Token.Kind == token.Invalid {
			to, err := f.evaluateRight(index.Children[1])

			if err != nil {
				return nil, err
			}

			if !types.Is(to.Type(), types.AnyInt) {
				return nil, errors.New(&TypeMismatch{Encountered: to.Type().Name(), Expected: types.AnyInt.Name()}, f.File, index.Children[1].Source())
			}

			elementType := types.Unwrap(address.Type()).(*types.Pointer).To
			sliceType := f.Env.Slice(elementType)
			slice := f.makeStruct(sliceType, []ssa.Value{address, to}, expr.Source())
			return slice, nil
		}

		from, err := f.evaluateRight(index.Children[0])

		if err != nil {
			return nil, err
		}

		if !types.Is(from.Type(), types.AnyInt) {
			return nil, errors.New(&TypeMismatch{Encountered: from.Type().Name(), Expected: types.AnyInt.Name()}, f.File, index.Children[0].Source())
		}

		to, err := f.evaluateRight(index.Children[1])

		if err != nil {
			return nil, err
		}

		if !types.Is(to.Type(), types.AnyInt) {
			return nil, errors.New(&TypeMismatch{Encountered: to.Type().Name(), Expected: types.AnyInt.Name()}, f.File, index.Children[1].Source())
		}

		return f.makeSlice(address, from, to, expr.Source()), nil
	}

	return nil, errors.New(InvalidExpression, f.File, expr.Source())
}