// Copyright IBM Corp. 2019, 2026
// SPDX-License-Identifier: MPL-2.0

package tfjson

import (
	"encoding/json"
	"errors"
)

// Config represents the complete configuration source.
type Config struct {
	// A map of all provider instances across all modules in the
	// configuration.
	//
	// The index for this field is opaque and should not be parsed. Use
	// the individual fields in ProviderConfig to discern actual data
	// about the provider such as name, alias, or defined module.
	ProviderConfigs map[string]*ProviderConfig `json:"provider_config,omitempty"`

	// The root module in the configuration. Any child modules descend
	// off of here.
	RootModule *ConfigModule `json:"root_module,omitempty"`
}

// Validate checks to ensure that the config is present.
func (c *Config) Validate() error {
	if c == nil {
		return errors.New("config is nil")
	}

	return nil
}

// UnmarshalJSON implements json.Unmarshaler for Config.
//
// As per established convention this method should only ever
// be invoked *indirectly* via [encoding/json] library.
func (c *Config) UnmarshalJSON(b []byte) error {
	type rawConfig Config
	var config rawConfig

	err := json.Unmarshal(b, &config)
	if err != nil {
		return err
	}

	*c = *(*Config)(&config)

	return c.Validate()
}

// ProviderConfig describes a provider configuration instance.
type ProviderConfig struct {
	// The name of the provider, ie: "aws".
	Name string `json:"name,omitempty"`

	// The fully-specified name of the provider, ie: "registry.terraform.io/hashicorp/aws".
	FullName string `json:"full_name,omitempty"`

	// The alias of the provider, ie: "us-east-1".
	Alias string `json:"alias,omitempty"`

	// The address of the module the provider is declared in.
	ModuleAddress string `json:"module_address,omitempty"`

	// Any non-special configuration values in the provider, indexed by
	// key.
	Expressions map[string]*Expression `json:"expressions,omitempty"`

	// The defined version constraint for this provider.
	VersionConstraint string `json:"version_constraint,omitempty"`
}

// ConfigModule describes a module in Terraform configuration.
type ConfigModule struct {
	// The outputs defined in the module.
	Outputs map[string]*ConfigOutput `json:"outputs,omitempty"`

	// The resources defined in the module.
	Resources []*ConfigResource `json:"resources,omitempty"`

	// Any "module" stanzas within the specific module.
	ModuleCalls map[string]*ModuleCall `json:"module_calls,omitempty"`

	// The variables defined in the module.
	Variables map[string]*ConfigVariable `json:"variables,omitempty"`
}

// ConfigOutput defines an output as defined in configuration.
type ConfigOutput struct {
	// Indicates whether or not the output was marked as sensitive.
	Sensitive bool `json:"sensitive,omitempty"`

	// The defined value of the output.
	Expression *Expression `json:"expression,omitempty"`

	// The defined description of this output.
	Description string `json:"description,omitempty"`

	// The defined dependencies tied to this output.
	DependsOn []string `json:"depends_on,omitempty"`
}

// ConfigResource is the configuration representation of a resource.
type ConfigResource struct {
	// The address of the resource relative to the module that it is
	// in.
	Address string `json:"address,omitempty"`

	// The resource mode.
	Mode ResourceMode `json:"mode,omitempty"`

	// The type of resource, ie: "null_resource" in
	// "null_resource.foo".
	Type string `json:"type,omitempty"`

	// The name of the resource, ie: "foo" in "null_resource.foo".
	Name string `json:"name,omitempty"`

	// An opaque key representing the provider configuration this
	// module uses. Note that there are more than one circumstance that
	// this key will not match what is found in the ProviderConfigs
	// field in the root Config structure, and as such should not be
	// relied on for that purpose.
	ProviderConfigKey string `json:"provider_config_key,omitempty"`

	// The list of provisioner defined for this configuration. This
	// will be nil if no providers are defined.
	Provisioners []*ConfigProvisioner `json:"provisioners,omitempty"`

	// Any non-special configuration values in the resource, indexed by
	// key.
	Expressions map[string]*Expression `json:"expressions,omitempty"`

	// The resource's configuration schema version. With access to the
	// specific Terraform provider for this resource, this can be used
	// to determine the correct schema for the configuration data
	// supplied in Expressions.
	SchemaVersion uint64 `json:"schema_version"`

	// The expression data for the "count" value in the resource.
	CountExpression *Expression `json:"count_expression,omitempty"`

	// The expression data for the "for_each" value in the resource.
	ForEachExpression *Expression `json:"for_each_expression,omitempty"`

	// The contents of the "depends_on" config directive, which
	// declares explicit dependencies for this resource.
	DependsOn []string `json:"depends_on,omitempty"`
}

// ConfigVariable defines a variable as defined in configuration.
type ConfigVariable struct {
	// The defined default value of the variable.
	Default interface{} `json:"default,omitempty"`

	// The defined text description of the variable.
	Description string `json:"description,omitempty"`

	// Whether the variable is marked as sensitive
	Sensitive bool `json:"sensitive,omitempty"`
}

// ConfigProvisioner describes a provisioner declared in a resource
// configuration.
type ConfigProvisioner struct {
	// The type of the provisioner, ie: "local-exec".
	Type string `json:"type,omitempty"`

	// Any non-special configuration values in the provisioner, indexed by
	// key.
	Expressions map[string]*Expression `json:"expressions,omitempty"`
}

// ModuleCall describes a declared "module" within a configuration.
// It also contains the data for the module itself.
type ModuleCall struct {
	// The contents of the "source" field.
	Source string `json:"source,omitempty"`

	// Any non-special configuration values in the module, indexed by
	// key.
	Expressions map[string]*Expression `json:"expressions,omitempty"`

	// The expression data for the "count" value in the module.
	CountExpression *Expression `json:"count_expression,omitempty"`

	// The expression data for the "for_each" value in the module.
	ForEachExpression *Expression `json:"for_each_expression,omitempty"`

	// The configuration data for the module itself.
	Module *ConfigModule `json:"module,omitempty"`

	// The version constraint for modules that come from the registry.
	VersionConstraint string `json:"version_constraint,omitempty"`

	// The explicit resource dependencies for the "depends_on" value.
	// As it must be a slice of references, Expression is not used.
	DependsOn []string `json:"depends_on,omitempty"`
}