package terraform

import (
	"fmt"

	"github.com/hashicorp/hcl/v2"
	"github.com/hashicorp/terraform/addrs"
	"github.com/hashicorp/terraform/configs"
	"github.com/hashicorp/terraform/configs/configschema"
	"github.com/hashicorp/terraform/providers"
	"github.com/hashicorp/terraform/provisioners"
	"github.com/hashicorp/terraform/tfdiags"
	"github.com/zclconf/go-cty/cty"
)

// NodeValidatableResource represents a resource that is used for validation
// only.
type NodeValidatableResource struct {
	*NodeAbstractResource
}

var (
	_ GraphNodeModuleInstance            = (*NodeValidatableResource)(nil)
	_ GraphNodeExecutable                = (*NodeValidatableResource)(nil)
	_ GraphNodeReferenceable             = (*NodeValidatableResource)(nil)
	_ GraphNodeReferencer                = (*NodeValidatableResource)(nil)
	_ GraphNodeConfigResource            = (*NodeValidatableResource)(nil)
	_ GraphNodeAttachResourceConfig      = (*NodeValidatableResource)(nil)
	_ GraphNodeAttachProviderMetaConfigs = (*NodeValidatableResource)(nil)
)

func (n *NodeValidatableResource) Path() addrs.ModuleInstance {
	// There is no expansion during validation, so we evaluate everything as
	// single module instances.
	return n.Addr.Module.UnkeyedInstanceShim()
}

// GraphNodeEvalable
func (n *NodeValidatableResource) Execute(ctx EvalContext, op walkOperation) (diags tfdiags.Diagnostics) {
	diags = diags.Append(n.validateResource(ctx))

	if managed := n.Config.Managed; managed != nil {
		hasCount := n.Config.Count != nil
		hasForEach := n.Config.ForEach != nil

		// Validate all the provisioners
		for _, p := range managed.Provisioners {
			if p.Connection == nil {
				p.Connection = n.Config.Managed.Connection
			} else if n.Config.Managed.Connection != nil {
				p.Connection.Config = configs.MergeBodies(n.Config.Managed.Connection.Config, p.Connection.Config)
			}

			// Validate Provisioner Config
			diags = diags.Append(n.validateProvisioner(ctx, p, hasCount, hasForEach))
			if diags.HasErrors() {
				return diags
			}
		}
	}
	return diags
}

// validateProvisioner validates the configuration of a provisioner belonging to
// a resource. The provisioner config is expected to contain the merged
// connection configurations.
func (n *NodeValidatableResource) validateProvisioner(ctx EvalContext, p *configs.Provisioner, hasCount, hasForEach bool) tfdiags.Diagnostics {
	var diags tfdiags.Diagnostics

	provisioner, err := ctx.Provisioner(p.Type)
	if err != nil {
		diags = diags.Append(err)
		return diags
	}

	if provisioner == nil {
		return diags.Append(fmt.Errorf("provisioner %s not initialized", p.Type))
	}
	provisionerSchema := ctx.ProvisionerSchema(p.Type)
	if provisionerSchema == nil {
		return diags.Append(fmt.Errorf("provisioner %s not initialized", p.Type))
	}

	// Validate the provisioner's own config first
	configVal, _, configDiags := n.evaluateBlock(ctx, p.Config, provisionerSchema, hasCount, hasForEach)
	diags = diags.Append(configDiags)

	if configVal == cty.NilVal {
		// Should never happen for a well-behaved EvaluateBlock implementation
		return diags.Append(fmt.Errorf("EvaluateBlock returned nil value"))
	}

	// Use unmarked value for validate request
	unmarkedConfigVal, _ := configVal.UnmarkDeep()
	req := provisioners.ValidateProvisionerConfigRequest{
		Config: unmarkedConfigVal,
	}

	resp := provisioner.ValidateProvisionerConfig(req)
	diags = diags.Append(resp.Diagnostics)

	if p.Connection != nil {
		// We can't comprehensively validate the connection config since its
		// final structure is decided by the communicator and we can't instantiate
		// that until we have a complete instance state. However, we *can* catch
		// configuration keys that are not valid for *any* communicator, catching
		// typos early rather than waiting until we actually try to run one of
		// the resource's provisioners.
		_, _, connDiags := n.evaluateBlock(ctx, p.Connection.Config, connectionBlockSupersetSchema, hasCount, hasForEach)
		diags = diags.Append(connDiags)
	}
	return diags
}

func (n *NodeValidatableResource) evaluateBlock(ctx EvalContext, body hcl.Body, schema *configschema.Block, hasCount, hasForEach bool) (cty.Value, hcl.Body, tfdiags.Diagnostics) {
	keyData := EvalDataForNoInstanceKey
	selfAddr := n.ResourceAddr().Resource.Instance(addrs.NoKey)

	if hasCount {
		// For a resource that has count, we allow count.index but don't
		// know at this stage what it will return.
		keyData = InstanceKeyEvalData{
			CountIndex: cty.UnknownVal(cty.Number),
		}

		// "self" can't point to an unknown key, but we'll force it to be
		// key 0 here, which should return an unknown value of the
		// expected type since none of these elements are known at this
		// point anyway.
		selfAddr = n.ResourceAddr().Resource.Instance(addrs.IntKey(0))
	} else if hasForEach {
		// For a resource that has for_each, we allow each.value and each.key
		// but don't know at this stage what it will return.
		keyData = InstanceKeyEvalData{
			EachKey:   cty.UnknownVal(cty.String),
			EachValue: cty.DynamicVal,
		}

		// "self" can't point to an unknown key, but we'll force it to be
		// key "" here, which should return an unknown value of the
		// expected type since none of these elements are known at
		// this point anyway.
		selfAddr = n.ResourceAddr().Resource.Instance(addrs.StringKey(""))
	}

	return ctx.EvaluateBlock(body, schema, selfAddr, keyData)
}

// connectionBlockSupersetSchema is a schema representing the superset of all
// possible arguments for "connection" blocks across all supported connection
// types.
//
// This currently lives here because we've not yet updated our communicator
// subsystem to be aware of schema itself. Once that is done, we can remove
// this and use a type-specific schema from the communicator to validate
// exactly what is expected for a given connection type.
var connectionBlockSupersetSchema = &configschema.Block{
	Attributes: map[string]*configschema.Attribute{
		// NOTE: "type" is not included here because it's treated special
		// by the config loader and stored away in a separate field.

		// Common attributes for both connection types
		"host": {
			Type:     cty.String,
			Required: true,
		},
		"type": {
			Type:     cty.String,
			Optional: true,
		},
		"user": {
			Type:     cty.String,
			Optional: true,
		},
		"password": {
			Type:     cty.String,
			Optional: true,
		},
		"port": {
			Type:     cty.String,
			Optional: true,
		},
		"timeout": {
			Type:     cty.String,
			Optional: true,
		},
		"script_path": {
			Type:     cty.String,
			Optional: true,
		},
		// For type=ssh only (enforced in ssh communicator)
		"target_platform": {
			Type:     cty.String,
			Optional: true,
		},
		"private_key": {
			Type:     cty.String,
			Optional: true,
		},
		"certificate": {
			Type:     cty.String,
			Optional: true,
		},
		"host_key": {
			Type:     cty.String,
			Optional: true,
		},
		"agent": {
			Type:     cty.Bool,
			Optional: true,
		},
		"agent_identity": {
			Type:     cty.String,
			Optional: true,
		},
		"bastion_host": {
			Type:     cty.String,
			Optional: true,
		},
		"bastion_host_key": {
			Type:     cty.String,
			Optional: true,
		},
		"bastion_port": {
			Type:     cty.Number,
			Optional: true,
		},
		"bastion_user": {
			Type:     cty.String,
			Optional: true,
		},
		"bastion_password": {
			Type:     cty.String,
			Optional: true,
		},
		"bastion_private_key": {
			Type:     cty.String,
			Optional: true,
		},
		"bastion_certificate": {
			Type:     cty.String,
			Optional: true,
		},

		// For type=winrm only (enforced in winrm communicator)
		"https": {
			Type:     cty.Bool,
			Optional: true,
		},
		"insecure": {
			Type:     cty.Bool,
			Optional: true,
		},
		"cacert": {
			Type:     cty.String,
			Optional: true,
		},
		"use_ntlm": {
			Type:     cty.Bool,
			Optional: true,
		},
	},
}

func (n *NodeValidatableResource) validateResource(ctx EvalContext) tfdiags.Diagnostics {
	var diags tfdiags.Diagnostics

	provider, providerSchema, err := getProvider(ctx, n.ResolvedProvider)
	diags = diags.Append(err)
	if diags.HasErrors() {
		return diags
	}
	if providerSchema == nil {
		diags = diags.Append(fmt.Errorf("validateResource has nil schema for %s", n.Addr))
		return diags
	}

	keyData := EvalDataForNoInstanceKey

	switch {
	case n.Config.Count != nil:
		// If the config block has count, we'll evaluate with an unknown
		// number as count.index so we can still type check even though
		// we won't expand count until the plan phase.
		keyData = InstanceKeyEvalData{
			CountIndex: cty.UnknownVal(cty.Number),
		}

		// Basic type-checking of the count argument. More complete validation
		// of this will happen when we DynamicExpand during the plan walk.
		countDiags := validateCount(ctx, n.Config.Count)
		diags = diags.Append(countDiags)

	case n.Config.ForEach != nil:
		keyData = InstanceKeyEvalData{
			EachKey:   cty.UnknownVal(cty.String),
			EachValue: cty.UnknownVal(cty.DynamicPseudoType),
		}

		// Evaluate the for_each expression here so we can expose the diagnostics
		forEachDiags := validateForEach(ctx, n.Config.ForEach)
		diags = diags.Append(forEachDiags)
	}

	diags = diags.Append(validateDependsOn(ctx, n.Config.DependsOn))

	// Validate the provider_meta block for the provider this resource
	// belongs to, if there is one.
	//
	// Note: this will return an error for every resource a provider
	// uses in a module, if the provider_meta for that module is
	// incorrect. The only way to solve this that we've found is to
	// insert a new ProviderMeta graph node in the graph, and make all
	// that provider's resources in the module depend on the node. That's
	// an awful heavy hammer to swing for this feature, which should be
	// used only in limited cases with heavy coordination with the
	// Terraform team, so we're going to defer that solution for a future
	// enhancement to this functionality.
	/*
		if n.ProviderMetas != nil {
			if m, ok := n.ProviderMetas[n.ProviderAddr.ProviderConfig.Type]; ok && m != nil {
				// if the provider doesn't support this feature, throw an error
				if (*n.ProviderSchema).ProviderMeta == nil {
					diags = diags.Append(&hcl.Diagnostic{
						Severity: hcl.DiagError,
						Summary:  fmt.Sprintf("Provider %s doesn't support provider_meta", cfg.ProviderConfigAddr()),
						Detail:   fmt.Sprintf("The resource %s belongs to a provider that doesn't support provider_meta blocks", n.Addr),
						Subject:  &m.ProviderRange,
					})
				} else {
					_, _, metaDiags := ctx.EvaluateBlock(m.Config, (*n.ProviderSchema).ProviderMeta, nil, EvalDataForNoInstanceKey)
					diags = diags.Append(metaDiags)
				}
			}
		}
	*/
	// BUG(paddy): we're not validating provider_meta blocks on EvalValidate right now
	// because the ProviderAddr for the resource isn't available on the EvalValidate
	// struct.

	// Provider entry point varies depending on resource mode, because
	// managed resources and data resources are two distinct concepts
	// in the provider abstraction.
	switch n.Config.Mode {
	case addrs.ManagedResourceMode:
		schema, _ := providerSchema.SchemaForResourceType(n.Config.Mode, n.Config.Type)
		if schema == nil {
			diags = diags.Append(&hcl.Diagnostic{
				Severity: hcl.DiagError,
				Summary:  "Invalid resource type",
				Detail:   fmt.Sprintf("The provider %s does not support resource type %q.", n.Config.ProviderConfigAddr(), n.Config.Type),
				Subject:  &n.Config.TypeRange,
			})
			return diags
		}

		configVal, _, valDiags := ctx.EvaluateBlock(n.Config.Config, schema, nil, keyData)
		diags = diags.Append(valDiags)
		if valDiags.HasErrors() {
			return diags
		}

		if n.Config.Managed != nil { // can be nil only in tests with poorly-configured mocks
			for _, traversal := range n.Config.Managed.IgnoreChanges {
				// validate the ignore_changes traversals apply.
				moreDiags := schema.StaticValidateTraversal(traversal)
				diags = diags.Append(moreDiags)

				// TODO: we want to notify users that they can't use
				// ignore_changes for computed attributes, but we don't have an
				// easy way to correlate the config value, schema and
				// traversal together.
			}
		}

		// Use unmarked value for validate request
		unmarkedConfigVal, _ := configVal.UnmarkDeep()
		req := providers.ValidateResourceConfigRequest{
			TypeName: n.Config.Type,
			Config:   unmarkedConfigVal,
		}

		resp := provider.ValidateResourceConfig(req)
		diags = diags.Append(resp.Diagnostics.InConfigBody(n.Config.Config, n.Addr.String()))

	case addrs.DataResourceMode:
		schema, _ := providerSchema.SchemaForResourceType(n.Config.Mode, n.Config.Type)
		if schema == nil {
			diags = diags.Append(&hcl.Diagnostic{
				Severity: hcl.DiagError,
				Summary:  "Invalid data source",
				Detail:   fmt.Sprintf("The provider %s does not support data source %q.", n.Config.ProviderConfigAddr(), n.Config.Type),
				Subject:  &n.Config.TypeRange,
			})
			return diags
		}

		configVal, _, valDiags := ctx.EvaluateBlock(n.Config.Config, schema, nil, keyData)
		diags = diags.Append(valDiags)
		if valDiags.HasErrors() {
			return diags
		}

		// Use unmarked value for validate request
		unmarkedConfigVal, _ := configVal.UnmarkDeep()
		req := providers.ValidateDataResourceConfigRequest{
			TypeName: n.Config.Type,
			Config:   unmarkedConfigVal,
		}

		resp := provider.ValidateDataResourceConfig(req)
		diags = diags.Append(resp.Diagnostics.InConfigBody(n.Config.Config, n.Addr.String()))
	}

	return diags
}

func validateCount(ctx EvalContext, expr hcl.Expression) (diags tfdiags.Diagnostics) {
	val, countDiags := evaluateCountExpressionValue(expr, ctx)
	// If the value isn't known then that's the best we can do for now, but
	// we'll check more thoroughly during the plan walk
	if !val.IsKnown() {
		return diags
	}

	if countDiags.HasErrors() {
		diags = diags.Append(countDiags)
	}

	return diags
}

func validateForEach(ctx EvalContext, expr hcl.Expression) (diags tfdiags.Diagnostics) {
	val, forEachDiags := evaluateForEachExpressionValue(expr, ctx, true)
	// If the value isn't known then that's the best we can do for now, but
	// we'll check more thoroughly during the plan walk
	if !val.IsKnown() {
		return diags
	}

	if forEachDiags.HasErrors() {
		diags = diags.Append(forEachDiags)
	}

	return diags
}

func validateDependsOn(ctx EvalContext, dependsOn []hcl.Traversal) (diags tfdiags.Diagnostics) {
	for _, traversal := range dependsOn {
		ref, refDiags := addrs.ParseRef(traversal)
		diags = diags.Append(refDiags)
		if !refDiags.HasErrors() && len(ref.Remaining) != 0 {
			diags = diags.Append(&hcl.Diagnostic{
				Severity: hcl.DiagError,
				Summary:  "Invalid depends_on reference",
				Detail:   "References in depends_on must be to a whole object (resource, etc), not to an attribute of an object.",
				Subject:  ref.Remaining.SourceRange().Ptr(),
			})
		}

		// The ref must also refer to something that exists. To test that,
		// we'll just eval it and count on the fact that our evaluator will
		// detect references to non-existent objects.
		if !diags.HasErrors() {
			scope := ctx.EvaluationScope(nil, EvalDataForNoInstanceKey)
			if scope != nil { // sometimes nil in tests, due to incomplete mocks
				_, refDiags = scope.EvalReference(ref, cty.DynamicPseudoType)
				diags = diags.Append(refDiags)
			}
		}
	}
	return diags
}
