terraform-provider-hashicups/internal/provider/order_resource.go

package provider

import (
	"context"
	"fmt"
	"strconv"
	"time"

	"github.com/hashicorp-demoapp/hashicups-client-go"
	"github.com/hashicorp/terraform-plugin-framework/resource"
	"github.com/hashicorp/terraform-plugin-framework/resource/schema"
	"github.com/hashicorp/terraform-plugin-framework/types"
)

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

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

type orderResource struct {
	client *hashicups.Client
}

func (r *orderResource) Configure(ctx context.Context, req resource.ConfigureRequest, resp *resource.ConfigureResponse) {
	// Add a nil check when handling ProviderData because Terraform
	// sets that data after it calls the ConfigureProvider RPC.
	if req.ProviderData == nil {
		return
	}

	client, ok := req.ProviderData.(*hashicups.Client)
	if !ok {
		resp.Diagnostics.AddError("Unexpected Resource Configure Type",
			fmt.Sprintf("Expected *hashicups.Client, got: %T. Please report this issue to the provider developers.", req.ProviderData))
		return
	}
	r.client = client
}

func (r *orderResource) Metadata(ctx context.Context, req resource.MetadataRequest, resp *resource.MetadataResponse) {
	resp.TypeName = req.ProviderTypeName + "_order"
}

func (r *orderResource) Schema(ctx context.Context, req resource.SchemaRequest, resp *resource.SchemaResponse) {
	resp.Schema = schema.Schema{
		Attributes: map[string]schema.Attribute{
			"id": schema.StringAttribute{
				Computed: true,
			},
			"last_updated": schema.StringAttribute{
				Computed: true,
			},
			"items": schema.ListNestedAttribute{
				Required: true,
				NestedObject: schema.NestedAttributeObject{
					Attributes: map[string]schema.Attribute{
						"quantity": schema.Int64Attribute{
							Required: true,
						},
						"coffee": schema.SingleNestedAttribute{
							Required: true,
							Attributes: map[string]schema.Attribute{
								"id": schema.Int64Attribute{
									Required: true,
								},
								"name": schema.StringAttribute{
									Computed: true,
								},
								"teaser": schema.StringAttribute{
									Computed: true,
								},
								"description": schema.StringAttribute{
									Computed: true,
								},
								"price": schema.Float64Attribute{
									Computed: true,
								},
								"image": schema.StringAttribute{
									Computed: true,
								},
							},
						},
					},
				},
			},
		},
	}
}

func (r *orderResource) Create(ctx context.Context, req resource.CreateRequest, resp *resource.CreateResponse) {
	var plan orderResourceModel

	// 1. Checks whether the API Client is configured.
	if r.client == nil {
		resp.Diagnostics.AddError(
			"cannot create order",
			"client is not configured in orderResource.Create",
		)
		return
	}

	// 2. Retrieves values from the plan.
	// The function will attempt to retrieve values from the plan and convert it to an orderResourceModel.
	// If not, the resource responds with an error.
	diags := req.Plan.Get(ctx, &plan)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}

	// 3. Generates an API request body from the plan values.
	// The function loops through each plan item and maps it to a hashicups.OrderItem.
	// This is what the API client needs to create a new order.
	var items []hashicups.OrderItem
	for _, item := range plan.Items {
		items = append(items, hashicups.OrderItem{
			Coffee: hashicups.Coffee{
				ID: int(item.Coffee.ID.ValueInt64()),
			},
			Quantity: int(item.Quantity.ValueInt64()),
		})
	}

	// 4. Creates a new order.
	// The function invokes the API client's CreateOrder method.
	order, err := r.client.CreateOrder(items)
	if err != nil {
		resp.Diagnostics.AddError(
			"Error creating order",
			err.Error(),
		)
		return
	}

	// 5. Maps response body to resource schema attributes.
	// After the function creates an order, it maps the hashicups.Order response to []OrderItem so the provider can update the Terraform state.
	plan.ID = types.StringValue(strconv.Itoa(order.ID))
	for orderItemIndex, orderItem := range order.Items {
		plan.Items[orderItemIndex] = orderItemModel{
			Coffee: orderItemCoffeeModel{
				ID:          types.Int64Value(int64(orderItem.Coffee.ID)),
				Name:        types.StringValue(orderItem.Coffee.Name),
				Teaser:      types.StringValue(orderItem.Coffee.Teaser),
				Description: types.StringValue(orderItem.Coffee.Description),
				Price:       types.Float64Value(orderItem.Coffee.Price),
				Image:       types.StringValue(orderItem.Coffee.Image),
			},
			Quantity: types.Int64Value(int64(orderItem.Quantity)),
		}
	}
	plan.LastUpdated = types.StringValue(time.Now().Format(time.RFC850)) // Why not RFC3339 ?

	// 6. Sets Terraform's state with the new order's details.
	diags = resp.State.Set(ctx, plan)
	resp.Diagnostics.Append(diags...)

	// Useless code in tutorial, why ?
	if resp.Diagnostics.HasError() {
		return
	}
}

func (r *orderResource) Read(ctx context.Context, req resource.ReadRequest, resp *resource.ReadResponse) {
	var state orderResourceModel

	// 0. Checks whether the API Client is configured.
	if r.client == nil {
		resp.Diagnostics.AddError(
			"cannot read order",
			"client is not configured in orderResource.Read",
		)
		return
	}

	// 1. Gets the current state.
	// If it is unable to, the provider responds with an error.
	diags := req.State.Get(ctx, &state)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}

	// 2. Retrieves the order ID from Terraform's state.
	id := state.ID.ValueString()

	// 3. Retrieves the order details from the client.
	// The function invokes the API client's GetOrder method with the order ID.
	order, err := r.client.GetOrder(id)
	if err != nil {
		resp.Diagnostics.AddError(
			"Error reading HashiCups order",
			"Could not read HashiCups order "+state.ID.ValueString()+": "+err.Error(),
		)
		return
	}

	// 4. Maps the response body to resource schema attributes.
	// == overwrite items with refreshed state
	// After the function retrieves the order, it maps the hashicups.Order response to []OrderItem so the provider can update the Terraform state.
	state.Items = []orderItemModel{}
	for _, item := range order.Items {
		itemState := orderItemModel{
			Coffee: orderItemCoffeeModel{
				ID:          types.Int64Value(int64(item.Coffee.ID)),
				Name:        types.StringValue(item.Coffee.Name),
				Teaser:      types.StringValue(item.Coffee.Teaser),
				Description: types.StringValue(item.Coffee.Description),
				Price:       types.Float64Value(item.Coffee.Price),
				Image:       types.StringValue(item.Coffee.Image),
			},
			Quantity: types.Int64Value(int64(item.Quantity)),
		}
		state.Items = append(state.Items, itemState)
	}

	// 5. Set Terraform's state with the order's model.
	diags = resp.State.Set(ctx, state)
	resp.Diagnostics.Append(diags...)

	// Useless code in tutorial, why ?
	if resp.Diagnostics.HasError() {
		return
	}
}

func (r *orderResource) Update(ctx context.Context, req resource.UpdateRequest, resp *resource.UpdateResponse) {
	return
}

func (r *orderResource) Delete(ctx context.Context, req resource.DeleteRequest, resp *resource.DeleteResponse) {
	return
}

// The *Model types describe the types known by the API.
// They are basically DTOs for the TF provider to talk to the API, while
// its native type is the Plan with its Schema.
type orderResourceModel struct {
	ID          types.String     `tfsdk:"id"`
	Items       []orderItemModel `tfsdk:"items"`
	LastUpdated types.String     `tfsdk:"last_updated"`
}

type orderItemModel struct {
	Quantity types.Int64          `tfsdk:"quantity"`
	Coffee   orderItemCoffeeModel `tfsdk:"coffee"`
}

type orderItemCoffeeModel struct {
	ID          types.Int64   `tfsdk:"id"`
	Name        types.String  `tfsdk:"name"`
	Teaser      types.String  `tfsdk:"teaser"`
	Description types.String  `tfsdk:"description"`
	Price       types.Float64 `tfsdk:"price"`
	Image       types.String  `tfsdk:"image"`
}