// Copyright 2022 CUE Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package pkg

import (
	"iter"

	"cuelang.org/go/cue"
	"cuelang.org/go/internal/core/adt"
)

// A Schema represents an arbitrary cue.Value that can hold non-concrete values.
// By default function arguments are checked to be concrete.
type Schema = cue.Value

// List represents a CUE list, which can be open or closed.
type List struct {
	runtime adt.Runtime
	node    *adt.Vertex
	isOpen  bool
}

// Elems returns the elements of a list.
func (l *List) Elems() iter.Seq[*adt.Vertex] {
	return l.node.Elems()
}

// IsOpen reports whether a list is open ended.
func (l *List) IsOpen() bool {
	return l.isOpen
}

// Struct represents a CUE struct, which can be open or closed.
type Struct struct {
	runtime adt.Runtime
	node    *adt.Vertex
}

// Arcs returns all arcs of s.
func (s *Struct) Arcs() []*adt.Vertex {
	return s.node.Arcs
}

// Len reports the number of regular string fields of s.
func (s *Struct) Len() int {
	count := 0
	for _, a := range s.Arcs() {
		if a.Label.IsString() && !s.node.IsOptional(a.Label) {
			count++
		}
	}
	return count
}

// IsOpen reports whether s is open or has pattern constraints.
func (s *Struct) IsOpen() bool {
	if s.node.IsOpenStruct() {
		return true
	}
	// Check for pattern constraints which indicate openness.
	if s.node.PatternConstraints != nil && len(s.node.PatternConstraints.Pairs) > 0 {
		return true
	}
	// After removing OptionalTypes, we rely on other checks for openness.
	return false
}

// NumConstraintFields reports the number of explicit optional and required
// fields, excluding pattern constraints.
func (s Struct) NumConstraintFields() (count int) {
	// If we have any optional arcs, we allow more fields.
	for _, a := range s.node.Arcs {
		if a.ArcType != adt.ArcMember && a.Label.IsRegular() {
			count++
		}
	}
	return count
}

// A ValidationError indicates an error that is only valid if a builtin is used
// as a validator.
type ValidationError struct {
	B *adt.Bottom
}

func (v ValidationError) Error() string { return v.B.Err.Error() }