package network

import (
	"context"
	"fmt"
	"net/http"
	"strings"

	"github.com/hashicorp/terraform-plugin-framework-validators/stringvalidator"
	"github.com/hashicorp/terraform-plugin-framework/path"
	"github.com/hashicorp/terraform-plugin-framework/resource"
	"github.com/hashicorp/terraform-plugin-framework/resource/schema"
	"github.com/hashicorp/terraform-plugin-framework/resource/schema/planmodifier"
	"github.com/hashicorp/terraform-plugin-framework/resource/schema/stringplanmodifier"
	"github.com/hashicorp/terraform-plugin-framework/schema/validator"
	"github.com/hashicorp/terraform-plugin-framework/types"
	"github.com/hashicorp/terraform-plugin-log/tflog"
	"github.com/stackitcloud/stackit-sdk-go/core/config"
	"github.com/stackitcloud/stackit-sdk-go/core/oapierror"
	"github.com/stackitcloud/stackit-sdk-go/core/runtime"
	"github.com/stackitcloud/stackit-sdk-go/services/iaas"
	"github.com/stackitcloud/stackit-sdk-go/services/iaas/wait"
	"github.com/stackitcloud/terraform-provider-stackit/stackit/internal/conversion"
	"github.com/stackitcloud/terraform-provider-stackit/stackit/internal/core"
	"github.com/stackitcloud/terraform-provider-stackit/stackit/internal/utils"
	"github.com/stackitcloud/terraform-provider-stackit/stackit/internal/validate"
)

// Ensure the implementation satisfies the expected interfaces.
var (
	_ resource.Resource                = &networkResource{}
	_ resource.ResourceWithConfigure   = &networkResource{}
	_ resource.ResourceWithImportState = &networkResource{}
)

type Model struct {
	Id               types.String `tfsdk:"id"` // needed by TF
	ProjectId        types.String `tfsdk:"project_id"`
	NetworkId        types.String `tfsdk:"network_id"`
	Name             types.String `tfsdk:"name"`
	Nameservers      types.List   `tfsdk:"nameservers"`
	IPv4PrefixLength types.Int64  `tfsdk:"ipv4_prefix_length"`
	Prefixes         types.List   `tfsdk:"prefixes"`
	PublicIP         types.String `tfsdk:"public_ip"`
}

// NewNetworkResource is a helper function to simplify the provider implementation.
func NewNetworkResource() resource.Resource {
	return &networkResource{}
}

// networkResource is the resource implementation.
type networkResource struct {
	client *iaas.APIClient
}

// Metadata returns the resource type name.
func (r *networkResource) Metadata(_ context.Context, req resource.MetadataRequest, resp *resource.MetadataResponse) {
	resp.TypeName = req.ProviderTypeName + "_network"
}

// Configure adds the provider configured client to the resource.
func (r *networkResource) Configure(ctx context.Context, req resource.ConfigureRequest, resp *resource.ConfigureResponse) {
	// Prevent panic if the provider has not been configured.
	if req.ProviderData == nil {
		return
	}

	providerData, ok := req.ProviderData.(core.ProviderData)
	if !ok {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error configuring API client", fmt.Sprintf("Expected configure type stackit.ProviderData, got %T", req.ProviderData))
		return
	}

	var apiClient *iaas.APIClient
	var err error
	if providerData.IaaSCustomEndpoint != "" {
		ctx = tflog.SetField(ctx, "iaas_custom_endpoint", providerData.IaaSCustomEndpoint)
		apiClient, err = iaas.NewAPIClient(
			config.WithCustomAuth(providerData.RoundTripper),
			config.WithEndpoint(providerData.IaaSCustomEndpoint),
		)
	} else {
		apiClient, err = iaas.NewAPIClient(
			config.WithCustomAuth(providerData.RoundTripper),
			config.WithRegion(providerData.Region),
		)
	}

	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error configuring API client", fmt.Sprintf("Configuring client: %v. This is an error related to the provider configuration, not to the resource configuration", err))
		return
	}

	r.client = apiClient
	tflog.Info(ctx, "IaaS client configured")
}

// Schema defines the schema for the resource.
func (r *networkResource) Schema(_ context.Context, _ resource.SchemaRequest, resp *resource.SchemaResponse) {
	resp.Schema = schema.Schema{
		Description: "Network resource schema. Must have a `region` specified in the provider configuration.",
		Attributes: map[string]schema.Attribute{
			"id": schema.StringAttribute{
				Description: "Terraform's internal resource ID. It is structured as \"`project_id`,`network_id`\".",
				Computed:    true,
				PlanModifiers: []planmodifier.String{
					stringplanmodifier.UseStateForUnknown(),
				},
			},
			"project_id": schema.StringAttribute{
				Description: "STACKIT project ID to which the network is associated.",
				Required:    true,
				PlanModifiers: []planmodifier.String{
					stringplanmodifier.RequiresReplace(),
				},
				Validators: []validator.String{
					validate.UUID(),
					validate.NoSeparator(),
				},
			},
			"network_id": schema.StringAttribute{
				Description: "The network ID.",
				Computed:    true,
				PlanModifiers: []planmodifier.String{
					stringplanmodifier.UseStateForUnknown(),
				},
				Validators: []validator.String{
					validate.UUID(),
					validate.NoSeparator(),
				},
			},
			"name": schema.StringAttribute{
				Description: "The name of the network.",
				Required:    true,
				Validators: []validator.String{
					stringvalidator.LengthAtLeast(1),
					stringvalidator.LengthAtMost(63),
				},
			},
			"nameservers": schema.ListAttribute{
				Description: "The nameservers of the network.",
				Required:    true,
				ElementType: types.StringType,
			},
			"ipv4_prefix_length": schema.Int64Attribute{
				Description: "The IPv4 prefix length of the network.",
				Optional:    true,
			},
			"prefixes": schema.ListAttribute{
				Description: "The prefixes of the network.",
				Computed:    true,
				ElementType: types.StringType,
			},
			"public_ip": schema.StringAttribute{
				Description: "The public IP of the network.",
				Computed:    true,
			},
		},
	}
}

// Create creates the resource and sets the initial Terraform state.
func (r *networkResource) Create(ctx context.Context, req resource.CreateRequest, resp *resource.CreateResponse) { // nolint:gocritic // function signature required by Terraform
	// Retrieve values from plan
	var model Model
	diags := req.Plan.Get(ctx, &model)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}

	projectId := model.ProjectId.ValueString()
	ctx = tflog.SetField(ctx, "project_id", projectId)

	// Generate API request body from model
	payload, err := toCreatePayload(&model)
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error creating network", fmt.Sprintf("Creating API payload: %v", err))
		return
	}

	// Create new network
	var httpResp *http.Response
	ctxWithHTTPResp := runtime.WithCaptureHTTPResponse(ctx, &httpResp)
	_, err = r.client.CreateNetwork(ctxWithHTTPResp, projectId).CreateNetworkPayload(*payload).Execute()
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error creating network", fmt.Sprintf("Calling API: %v", err))
		return
	}

	network, err := wait.CreateNetworkWaitHandler(ctx, r.client, projectId, httpResp.Header.Get("x-request-id")).WaitWithContext(context.Background())
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error creating network", fmt.Sprintf("Network creation waiting: %v", err))
		return
	}
	networkId := *network.NetworkId
	ctx = tflog.SetField(ctx, "network_id", networkId)

	// Map response body to schema
	err = mapFields(ctx, network, &model)
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error creating network", fmt.Sprintf("Processing API payload: %v", err))
		return
	}
	// Set state to fully populated data
	diags = resp.State.Set(ctx, model)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}
	tflog.Info(ctx, "Network created")
}

// Read refreshes the Terraform state with the latest data.
func (r *networkResource) Read(ctx context.Context, req resource.ReadRequest, resp *resource.ReadResponse) { // nolint:gocritic // function signature required by Terraform
	var model Model
	diags := req.State.Get(ctx, &model)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}
	projectId := model.ProjectId.ValueString()
	networkId := model.NetworkId.ValueString()
	ctx = tflog.SetField(ctx, "project_id", projectId)
	ctx = tflog.SetField(ctx, "network_id", networkId)

	networkResp, err := r.client.GetNetwork(ctx, projectId, networkId).Execute()
	if err != nil {
		oapiErr, ok := err.(*oapierror.GenericOpenAPIError) //nolint:errorlint //complaining that error.As should be used to catch wrapped errors, but this error should not be wrapped
		if ok && oapiErr.StatusCode == http.StatusNotFound {
			resp.State.RemoveResource(ctx)
			return
		}
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error reading network", fmt.Sprintf("Calling API: %v", err))
		return
	}

	// Map response body to schema
	err = mapFields(ctx, networkResp, &model)
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error reading network", fmt.Sprintf("Processing API payload: %v", err))
		return
	}
	// Set refreshed state
	diags = resp.State.Set(ctx, model)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}
	tflog.Info(ctx, "Network read")
}

// Update updates the resource and sets the updated Terraform state on success.
func (r *networkResource) Update(ctx context.Context, req resource.UpdateRequest, resp *resource.UpdateResponse) { // nolint:gocritic // function signature required by Terraform
	// Retrieve values from plan
	var model Model
	diags := req.Plan.Get(ctx, &model)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}
	projectId := model.ProjectId.ValueString()
	networkId := model.NetworkId.ValueString()
	ctx = tflog.SetField(ctx, "project_id", projectId)
	ctx = tflog.SetField(ctx, "network_id", networkId)

	// Generate API request body from model
	payload, err := toUpdatePayload(&model)
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error updating network", fmt.Sprintf("Creating API payload: %v", err))
		return
	}
	// Update existing network
	err = r.client.PartialUpdateNetwork(ctx, projectId, networkId).PartialUpdateNetworkPayload(*payload).Execute()
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error updating network", fmt.Sprintf("Calling API: %v", err))
		return
	}
	waitResp, err := wait.UpdateNetworkWaitHandler(ctx, r.client, projectId, networkId).WaitWithContext(ctx)
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error updating network", fmt.Sprintf("Network update waiting: %v", err))
		return
	}

	err = mapFields(ctx, waitResp, &model)
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error updating network", fmt.Sprintf("Processing API payload: %v", err))
		return
	}
	diags = resp.State.Set(ctx, model)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}
	tflog.Info(ctx, "Network updated")
}

// Delete deletes the resource and removes the Terraform state on success.
func (r *networkResource) Delete(ctx context.Context, req resource.DeleteRequest, resp *resource.DeleteResponse) { // nolint:gocritic // function signature required by Terraform
	// Retrieve values from state
	var model Model
	diags := req.State.Get(ctx, &model)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}

	projectId := model.ProjectId.ValueString()
	networkId := model.NetworkId.ValueString()
	ctx = tflog.SetField(ctx, "project_id", projectId)
	ctx = tflog.SetField(ctx, "network_id", networkId)

	// Delete existing network
	err := r.client.DeleteNetwork(ctx, projectId, networkId).Execute()
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error deleting network", fmt.Sprintf("Calling API: %v", err))
		return
	}
	_, err = wait.DeleteNetworkWaitHandler(ctx, r.client, projectId, networkId).WaitWithContext(ctx)
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error deleting network", fmt.Sprintf("Network deletion waiting: %v", err))
		return
	}

	tflog.Info(ctx, "Network deleted")
}

// ImportState imports a resource into the Terraform state on success.
// The expected format of the resource import identifier is: project_id,network_id
func (r *networkResource) ImportState(ctx context.Context, req resource.ImportStateRequest, resp *resource.ImportStateResponse) {
	idParts := strings.Split(req.ID, core.Separator)

	if len(idParts) != 2 || idParts[0] == "" || idParts[1] == "" {
		core.LogAndAddError(ctx, &resp.Diagnostics,
			"Error importing network",
			fmt.Sprintf("Expected import identifier with format: [project_id],[network_id]  Got: %q", req.ID),
		)
		return
	}

	projectId := idParts[0]
	networkId := idParts[1]
	ctx = tflog.SetField(ctx, "project_id", projectId)
	ctx = tflog.SetField(ctx, "network_id", networkId)

	resp.Diagnostics.Append(resp.State.SetAttribute(ctx, path.Root("project_id"), projectId)...)
	resp.Diagnostics.Append(resp.State.SetAttribute(ctx, path.Root("network_id"), networkId)...)
	tflog.Info(ctx, "Network state imported")
}

func mapFields(ctx context.Context, networkResp *iaas.Network, model *Model) error {
	if networkResp == nil {
		return fmt.Errorf("response input is nil")
	}
	if model == nil {
		return fmt.Errorf("model input is nil")
	}

	var networkId string
	if model.NetworkId.ValueString() != "" {
		networkId = model.NetworkId.ValueString()
	} else if networkResp.NetworkId != nil {
		networkId = *networkResp.NetworkId
	} else {
		return fmt.Errorf("network id not present")
	}

	idParts := []string{
		model.ProjectId.ValueString(),
		networkId,
	}
	model.Id = types.StringValue(
		strings.Join(idParts, core.Separator),
	)

	if networkResp.Nameservers == nil {
		model.Nameservers = types.ListNull(types.StringType)
	} else {
		respNameservers := *networkResp.Nameservers
		modelNameservers, err := utils.ListValuetoStringSlice(model.Nameservers)
		if err != nil {
			return fmt.Errorf("get current network nameservers from model: %w", err)
		}

		reconciledNameservers := utils.ReconcileStringSlices(modelNameservers, respNameservers)

		nameserversTF, diags := types.ListValueFrom(ctx, types.StringType, reconciledNameservers)
		if diags.HasError() {
			return fmt.Errorf("map network nameservers: %w", core.DiagsToError(diags))
		}

		model.Nameservers = nameserversTF
	}

	if networkResp.Prefixes == nil {
		model.Prefixes = types.ListNull(types.StringType)
	} else {
		respPrefixes := *networkResp.Prefixes
		prefixesTF, diags := types.ListValueFrom(ctx, types.StringType, respPrefixes)
		if diags.HasError() {
			return fmt.Errorf("map network prefixes: %w", core.DiagsToError(diags))
		}

		model.Prefixes = prefixesTF
	}

	model.NetworkId = types.StringValue(networkId)
	model.Name = types.StringPointerValue(networkResp.Name)
	model.PublicIP = types.StringPointerValue(networkResp.PublicIp)

	return nil
}

func toCreatePayload(model *Model) (*iaas.CreateNetworkPayload, error) {
	if model == nil {
		return nil, fmt.Errorf("nil model")
	}

	modelNameservers := []string{}
	for _, ns := range model.Nameservers.Elements() {
		nameserverString, ok := ns.(types.String)
		if !ok {
			return nil, fmt.Errorf("type assertion failed")
		}
		modelNameservers = append(modelNameservers, nameserverString.ValueString())
	}

	return &iaas.CreateNetworkPayload{
		Name: conversion.StringValueToPointer(model.Name),
		AddressFamily: &iaas.CreateNetworkAddressFamily{
			Ipv4: &iaas.CreateNetworkIPv4{
				PrefixLength: conversion.Int64ValueToPointer(model.IPv4PrefixLength),
				Nameservers:  &modelNameservers,
			},
		},
	}, nil
}

func toUpdatePayload(model *Model) (*iaas.PartialUpdateNetworkPayload, error) {
	if model == nil {
		return nil, fmt.Errorf("nil model")
	}

	modelNameservers := []string{}
	for _, ns := range model.Nameservers.Elements() {
		nameserverString, ok := ns.(types.String)
		if !ok {
			return nil, fmt.Errorf("type assertion failed")
		}
		modelNameservers = append(modelNameservers, nameserverString.ValueString())
	}

	return &iaas.PartialUpdateNetworkPayload{
		Name: conversion.StringValueToPointer(model.Name),
		AddressFamily: &iaas.UpdateNetworkAddressFamily{
			Ipv4: &iaas.UpdateNetworkIPv4{
				Nameservers: &modelNameservers,
			},
		},
	}, nil
}