model.go

// Package schemas defines JSON schema types.
//
// Code borrowed from https://github.com/alecthomas/jsonschema/
//
// # Copyright (C) 2014 Alec Thomas
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
// of the Software, and to permit persons to whom the Software is furnished to do
// so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
package schemas

import (
	"encoding/json"
	"fmt"
)

// Schema is the root schema.
type Schema struct {
	*ObjectAsType
	ID          string      `json:"$id"` // RFC draft-wright-json-schema-01, section-9.2.
	LegacyID    string      `json:"id"`  // RFC draft-wright-json-schema-00, section 4.5.
	Definitions Definitions `json:"$defs,omitempty"`
}

// UnmarshalJSON implements json.Unmarshaler for Schema struct.
func (s *Schema) UnmarshalJSON(data []byte) error {
	var unmarshSchema unmarshalerSchema
	if err := json.Unmarshal(data, &unmarshSchema); err != nil {
		return fmt.Errorf("failed to unmarshal schema: %w", err)
	}

	// Fall back to id if $id is not present.
	if unmarshSchema.ID == "" {
		unmarshSchema.ID = unmarshSchema.LegacyID
	}

	// Take care of legacy fields.
	var legacySchema struct {
		Definitions Definitions `json:"definitions,omitempty"`
	}

	if err := json.Unmarshal(data, &legacySchema); err != nil {
		return fmt.Errorf("failed to unmarshal schema: %w", err)
	}

	if unmarshSchema.Definitions == nil && legacySchema.Definitions != nil {
		unmarshSchema.Definitions = legacySchema.Definitions
	}

	*s = Schema(unmarshSchema)

	return nil
}

type (
	unmarshalerSchema Schema
	ObjectAsType      Type
)

// TypeList is a list of type names.
type TypeList []string

// UnmarshalJSON implements json.Unmarshaler.
func (t *TypeList) UnmarshalJSON(b []byte) error {
	if len(b) > 0 && b[0] == '[' {
		var s []string
		if err := json.Unmarshal(b, &s); err != nil {
			return fmt.Errorf("failed to unmarshal type list: %w", err)
		}

		*t = s

		return nil
	}

	var s string
	if err := json.Unmarshal(b, &s); err != nil {
		return fmt.Errorf("failed to unmarshal type list: %w", err)
	}

	if s != "" {
		*t = []string{s}
	} else {
		*t = nil
	}

	return nil
}

// Definitions hold schema definitions.
// http://json-schema.org/latest/json-schema-validation.html#rfc.section.5.26
// RFC draft-wright-json-schema-validation-00, section 5.26.
type Definitions map[string]*Type

// Type represents a JSON Schema object type.
type Type struct {
	// RFC draft-wright-json-schema-00.
	Version string `json:"$schema,omitempty"` // Section 6.1.
	Ref     string `json:"$ref,omitempty"`    // Section 7.
	// RFC draft-wright-json-schema-validation-00, section 5.
	MultipleOf           *float64         `json:"multipleOf,omitempty"`           // Section 5.1.
	Maximum              *float64         `json:"maximum,omitempty"`              // Section 5.2.
	ExclusiveMaximum     *any             `json:"exclusiveMaximum,omitempty"`     // Section 5.3. Changed in draft 4.
	Minimum              *float64         `json:"minimum,omitempty"`              // Section 5.4.
	ExclusiveMinimum     *any             `json:"exclusiveMinimum,omitempty"`     // Section 5.5. Changed in draft 4.
	MaxLength            int              `json:"maxLength,omitempty"`            // Section 5.6.
	MinLength            int              `json:"minLength,omitempty"`            // Section 5.7.
	Pattern              string           `json:"pattern,omitempty"`              // Section 5.8.
	AdditionalItems      *Type            `json:"additionalItems,omitempty"`      // Section 5.9.
	Items                *Type            `json:"items,omitempty"`                // Section 5.9.
	MaxItems             int              `json:"maxItems,omitempty"`             // Section 5.10.
	MinItems             int              `json:"minItems,omitempty"`             // Section 5.11.
	UniqueItems          bool             `json:"uniqueItems,omitempty"`          // Section 5.12.
	MaxProperties        int              `json:"maxProperties,omitempty"`        // Section 5.13.
	MinProperties        int              `json:"minProperties,omitempty"`        // Section 5.14.
	Required             []string         `json:"required,omitempty"`             // Section 5.15.
	Properties           map[string]*Type `json:"properties,omitempty"`           // Section 5.16.
	PatternProperties    map[string]*Type `json:"patternProperties,omitempty"`    // Section 5.17.
	AdditionalProperties *Type            `json:"additionalProperties,omitempty"` // Section 5.18.
	Enum                 []interface{}    `json:"enum,omitempty"`                 // Section 5.20.
	Type                 TypeList         `json:"type,omitempty"`                 // Section 5.21.
	AllOf                []*Type          `json:"allOf,omitempty"`                // Section 5.22.
	AnyOf                []*Type          `json:"anyOf,omitempty"`                // Section 5.23.
	OneOf                []*Type          `json:"oneOf,omitempty"`                // Section 5.24.
	Not                  *Type            `json:"not,omitempty"`                  // Section 5.25.
	// RFC draft-wright-json-schema-validation-00, section 6, 7.
	Title       string      `json:"title,omitempty"`       // Section 6.1.
	Description string      `json:"description,omitempty"` // Section 6.1.
	Default     interface{} `json:"default,omitempty"`     // Section 6.2.
	Format      string      `json:"format,omitempty"`      // Section 7.
	// RFC draft-wright-json-schema-hyperschema-00, section 4.
	Media          *Type  `json:"media,omitempty"`          // Section 4.3.
	BinaryEncoding string `json:"binaryEncoding,omitempty"` // Section 4.3.
	// RFC draft-handrews-json-schema-validation-02, section 6.
	DependentRequired map[string][]string `json:"dependentRequired,omitempty"` // Section 6.5.4.
	// RFC draft-handrews-json-schema-validation-02, appendix A.
	Definitions      Definitions      `json:"$defs,omitempty"`
	DependentSchemas map[string]*Type `json:"dependentSchemas,omitempty"`

	// ExtGoCustomType is the name of a (qualified or not) custom Go type
	// to use for the field.
	GoJSONSchemaExtension *GoJSONSchemaExtension `json:"goJSONSchema,omitempty"` //nolint:tagliatelle // breaking change
}

// UnmarshalJSON accepts booleans as schemas where `true` is equivalent to `{}`
// and `false` is equivalent to `{"not": {}}`.
func (value *Type) UnmarshalJSON(raw []byte) error {
	var b bool
	if err := json.Unmarshal(raw, &b); err == nil {
		if b {
			*value = Type{}
		} else {
			*value = Type{Not: &Type{}}
		}

		return nil
	}

	var obj ObjectAsType
	if err := json.Unmarshal(raw, &obj); err != nil {
		return fmt.Errorf("failed to unmarshal type: %w", err)
	}

	// Take care of legacy fields from older RFC versions.
	legacyObj := struct {
		// RFC draft-wright-json-schema-validation-00, section 5.
		Dependencies map[string]*Type `json:"dependencies,omitempty"`
		Definitions  Definitions      `json:"definitions,omitempty"` // Section 5.26.
	}{}
	if err := json.Unmarshal(raw, &legacyObj); err != nil {
		return fmt.Errorf("failed to unmarshal type: %w", err)
	}

	if legacyObj.Definitions != nil && obj.Definitions == nil {
		obj.Definitions = legacyObj.Definitions
	}

	if legacyObj.Dependencies != nil && obj.DependentSchemas == nil {
		obj.DependentSchemas = legacyObj.Dependencies
	}

	*value = Type(obj)

	return nil
}

type GoJSONSchemaExtension struct {
	Type       *string  `json:"type,omitempty"`
	Identifier *string  `json:"identifier,omitempty"`
	Nillable   bool     `json:"nillable,omitempty"`
	Imports    []string `json:"imports,omitempty"`
}