package objectstorage

import (
	"context"
	"fmt"
	"strings"
	"time"

	"github.com/hashicorp/terraform-plugin-framework/schema/validator"
	"github.com/hashicorp/terraform-plugin-log/tflog"
	"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/validate"

	"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/types"
	"github.com/stackitcloud/stackit-sdk-go/core/config"
	"github.com/stackitcloud/stackit-sdk-go/services/objectstorage"
)

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

type Model struct {
	Id                  types.String `tfsdk:"id"` // needed by TF
	CredentialId        types.String `tfsdk:"credential_id"`
	CredentialsGroupId  types.String `tfsdk:"credentials_group_id"`
	ProjectId           types.String `tfsdk:"project_id"`
	Name                types.String `tfsdk:"name"`
	AccessKey           types.String `tfsdk:"access_key"`
	SecretAccessKey     types.String `tfsdk:"secret_access_key"`
	ExpirationTimestamp types.String `tfsdk:"expiration_timestamp"`
}

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

// credentialResource is the resource implementation.
type credentialResource struct {
	client *objectstorage.APIClient
}

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

// Configure adds the provider configured client to the resource.
func (r *credentialResource) 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 *objectstorage.APIClient
	var err error
	if providerData.ObjectStorageCustomEndpoint != "" {
		apiClient, err = objectstorage.NewAPIClient(
			config.WithCustomAuth(providerData.RoundTripper),
			config.WithEndpoint(providerData.ObjectStorageCustomEndpoint),
		)
	} else {
		apiClient, err = objectstorage.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, "ObjectStorage credential client configured")
}

// Schema defines the schema for the resource.
func (r *credentialResource) Schema(_ context.Context, _ resource.SchemaRequest, resp *resource.SchemaResponse) {
	descriptions := map[string]string{
		"main":                 "ObjectStorage credential resource schema. Must have a `region` specified in the provider configuration.",
		"id":                   "Terraform's internal resource identifier. It is structured as \"`project_id`,`credentials_group_id`,`credential_id`\".",
		"credential_id":        "The credential ID.",
		"credentials_group_id": "The credential group ID.",
		"project_id":           "STACKIT Project ID to which the credential group is associated.",
		"expiration_timestamp": "Expiration timestamp, in RFC339 format without fractional seconds. Example: \"2025-01-01T00:00:00Z\". If not set, the credential never expires.",
	}

	resp.Schema = schema.Schema{
		Description: descriptions["main"],
		Attributes: map[string]schema.Attribute{
			"id": schema.StringAttribute{
				Description: descriptions["id"],
				Computed:    true,
				PlanModifiers: []planmodifier.String{
					stringplanmodifier.UseStateForUnknown(),
				},
			},
			"credential_id": schema.StringAttribute{
				Description: descriptions["credential_id"],
				Computed:    true,
				PlanModifiers: []planmodifier.String{
					stringplanmodifier.UseStateForUnknown(),
				},
				Validators: []validator.String{
					validate.UUID(),
					validate.NoSeparator(),
				},
			},
			"credentials_group_id": schema.StringAttribute{
				Description: descriptions["credentials_group_id"],
				Required:    true,
				PlanModifiers: []planmodifier.String{
					stringplanmodifier.UseStateForUnknown(),
				},
				Validators: []validator.String{
					validate.UUID(),
					validate.NoSeparator(),
				},
			},
			"project_id": schema.StringAttribute{
				Description: descriptions["project_id"],
				Required:    true,
				PlanModifiers: []planmodifier.String{
					stringplanmodifier.RequiresReplace(),
					stringplanmodifier.UseStateForUnknown(),
				},
				Validators: []validator.String{
					validate.UUID(),
					validate.NoSeparator(),
				},
			},
			"name": schema.StringAttribute{
				Computed: true,
			},
			"access_key": schema.StringAttribute{
				Computed: true,
			},
			"secret_access_key": schema.StringAttribute{
				Computed:  true,
				Sensitive: true,
			},
			"expiration_timestamp": schema.StringAttribute{
				Description: descriptions["expiration_timestamp"],
				Optional:    true,
				Computed:    true,
				Validators: []validator.String{
					validate.RFC3339SecondsOnly(),
				},
				PlanModifiers: []planmodifier.String{
					stringplanmodifier.UseStateForUnknown(),
				},
			},
		},
	}
}

// Create creates the resource and sets the initial Terraform state.
func (r *credentialResource) Create(ctx context.Context, req resource.CreateRequest, resp *resource.CreateResponse) { // nolint:gocritic // function signature required by Terraform
	var model Model
	diags := req.Plan.Get(ctx, &model)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}
	projectId := model.ProjectId.ValueString()
	credentialsGroupId := model.CredentialsGroupId.ValueString()
	ctx = tflog.SetField(ctx, "project_id", projectId)
	ctx = tflog.SetField(ctx, "credentials_group_id", credentialsGroupId)

	// Handle project init
	err := enableProject(ctx, &model, r.client)
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error creating credential", fmt.Sprintf("Enabling object storage project before creation: %v", err))
		return
	}

	// Generate API request body from model
	payload, err := toCreatePayload(&model)
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error creating credential", fmt.Sprintf("Creating API payload: %v", err))
		return
	}
	// Create new credential
	credentialResp, err := r.client.CreateAccessKey(ctx, projectId).CredentialsGroup(credentialsGroupId).CreateAccessKeyPayload(*payload).Execute()
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error creating credential", fmt.Sprintf("Calling API: %v", err))
		return
	}
	if credentialResp.KeyId == nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error creating credential", "Got empty credential id")
		return
	}
	credentialId := *credentialResp.KeyId
	ctx = tflog.SetField(ctx, "credential_id", credentialId)

	// Map response body to schema
	err = mapFields(credentialResp, &model)
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error creating credential", 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, "ObjectStorage credential created")
}

// Read refreshes the Terraform state with the latest data.
func (r *credentialResource) 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()
	credentialsGroupId := model.CredentialsGroupId.ValueString()
	credentialId := model.CredentialId.ValueString()
	ctx = tflog.SetField(ctx, "project_id", projectId)
	ctx = tflog.SetField(ctx, "credentials_group_id", credentialsGroupId)
	ctx = tflog.SetField(ctx, "credential_id", credentialId)

	found, err := readCredentials(ctx, &model, r.client)
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error reading credential", fmt.Sprintf("Finding credential: %v", err))
		return
	}
	if !found {
		resp.State.RemoveResource(ctx)
		return
	}

	// Set refreshed state
	diags = resp.State.Set(ctx, model)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}
	tflog.Info(ctx, "ObjectStorage credential read")
}

// Update updates the resource and sets the updated Terraform state on success.
func (r *credentialResource) Update(ctx context.Context, _ resource.UpdateRequest, resp *resource.UpdateResponse) { // nolint:gocritic // function signature required by Terraform
	// Update shouldn't be called
	core.LogAndAddError(ctx, &resp.Diagnostics, "Error updating credential", "Credential can't be updated")
}

// Delete deletes the resource and removes the Terraform state on success.
func (r *credentialResource) Delete(ctx context.Context, req resource.DeleteRequest, resp *resource.DeleteResponse) { // 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()
	credentialsGroupId := model.CredentialsGroupId.ValueString()
	credentialId := model.CredentialId.ValueString()
	ctx = tflog.SetField(ctx, "project_id", projectId)
	ctx = tflog.SetField(ctx, "credentials_group_id", credentialsGroupId)
	ctx = tflog.SetField(ctx, "credential_id", credentialId)

	// Delete existing credential
	_, err := r.client.DeleteAccessKey(ctx, projectId, credentialId).CredentialsGroup(credentialsGroupId).Execute()
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error deleting credential", fmt.Sprintf("Calling API: %v", err))
	}

	tflog.Info(ctx, "ObjectStorage credential deleted")
}

// ImportState imports a resource into the Terraform state on success.
// The expected format of the resource import identifier is: project_id,credentials_group_id,credential_id
func (r *credentialResource) ImportState(ctx context.Context, req resource.ImportStateRequest, resp *resource.ImportStateResponse) {
	idParts := strings.Split(req.ID, core.Separator)
	if len(idParts) != 3 || idParts[0] == "" || idParts[1] == "" || idParts[2] == "" {
		core.LogAndAddError(ctx, &resp.Diagnostics,
			"Error importing credential",
			fmt.Sprintf("Expected import identifier with format [project_id],[credentials_group_id],[credential_id], got %q", req.ID),
		)
		return
	}

	resp.Diagnostics.Append(resp.State.SetAttribute(ctx, path.Root("project_id"), idParts[0])...)
	resp.Diagnostics.Append(resp.State.SetAttribute(ctx, path.Root("credentials_group_id"), idParts[1])...)
	resp.Diagnostics.Append(resp.State.SetAttribute(ctx, path.Root("credential_id"), idParts[2])...)
	tflog.Info(ctx, "ObjectStorage credential state imported")
}

type objectStorageClient interface {
	EnableServiceExecute(ctx context.Context, projectId string) (*objectstorage.ProjectStatus, error)
}

// enableProject enables object storage for the specified project. If the project is already enabled, nothing happens
func enableProject(ctx context.Context, model *Model, client objectStorageClient) error {
	projectId := model.ProjectId.ValueString()

	// From the object storage OAS: Creation will also be successful if the project is already enabled, but will not create a duplicate
	_, err := client.EnableServiceExecute(ctx, projectId)
	if err != nil {
		return fmt.Errorf("failed to create object storage project: %w", err)
	}
	return nil
}

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

	if model.ExpirationTimestamp.IsNull() || model.ExpirationTimestamp.IsUnknown() {
		return &objectstorage.CreateAccessKeyPayload{}, nil
	}

	expirationTimestampValue := conversion.StringValueToPointer(model.ExpirationTimestamp)
	if expirationTimestampValue == nil {
		return &objectstorage.CreateAccessKeyPayload{}, nil
	}
	expirationTimestamp, err := time.Parse(time.RFC3339, *expirationTimestampValue)
	if err != nil {
		return nil, fmt.Errorf("unable to parse expiration timestamp '%v': %w", *expirationTimestampValue, err)
	}
	return &objectstorage.CreateAccessKeyPayload{
		Expires: &expirationTimestamp,
	}, nil
}

func mapFields(credentialResp *objectstorage.CreateAccessKeyResponse, model *Model) error {
	if credentialResp == nil {
		return fmt.Errorf("response input is nil")
	}
	if model == nil {
		return fmt.Errorf("model input is nil")
	}

	var credentialId string
	if model.CredentialId.ValueString() != "" {
		credentialId = model.CredentialId.ValueString()
	} else if credentialResp.KeyId != nil {
		credentialId = *credentialResp.KeyId
	} else {
		return fmt.Errorf("credential id not present")
	}

	if credentialResp.Expires == nil {
		model.ExpirationTimestamp = types.StringNull()
	} else {
		// Harmonize the timestamp format
		// Eg. "2027-01-02T03:04:05.000Z" = "2027-01-02T03:04:05Z"
		expirationTimestamp, err := time.Parse(time.RFC3339, *credentialResp.Expires)
		if err != nil {
			return fmt.Errorf("unable to parse payload expiration timestamp '%v': %w", *credentialResp.Expires, err)
		}
		model.ExpirationTimestamp = types.StringValue(expirationTimestamp.Format(time.RFC3339))
	}

	idParts := []string{
		model.ProjectId.ValueString(),
		model.CredentialsGroupId.ValueString(),
		credentialId,
	}
	model.Id = types.StringValue(
		strings.Join(idParts, core.Separator),
	)
	model.CredentialId = types.StringValue(credentialId)
	model.Name = types.StringPointerValue(credentialResp.DisplayName)
	model.AccessKey = types.StringPointerValue(credentialResp.AccessKey)
	model.SecretAccessKey = types.StringPointerValue(credentialResp.SecretAccessKey)
	return nil
}

// readCredentials gets all the existing credentials for the specified credentials group,
// finds the credential that is being read and updates the state.
// Returns True if the credential was found, False otherwise.
func readCredentials(ctx context.Context, model *Model, client *objectstorage.APIClient) (bool, error) {
	projectId := model.ProjectId.ValueString()
	credentialsGroupId := model.CredentialsGroupId.ValueString()
	credentialId := model.CredentialId.ValueString()

	credentialsGroupResp, err := client.ListAccessKeys(ctx, projectId).CredentialsGroup(credentialsGroupId).Execute()
	if err != nil {
		return false, fmt.Errorf("getting credentials groups: %w", err)
	}
	if credentialsGroupResp == nil {
		return false, fmt.Errorf("getting credentials groups: nil response")
	}

	foundCredential := false
	for _, credential := range *credentialsGroupResp.AccessKeys {
		if credential.KeyId == nil || *credential.KeyId != credentialId {
			continue
		}

		foundCredential = true

		idParts := []string{
			projectId,
			credentialsGroupId,
			credentialId,
		}
		model.Id = types.StringValue(
			strings.Join(idParts, core.Separator),
		)
		model.Name = types.StringPointerValue(credential.DisplayName)

		if credential.Expires == nil {
			model.ExpirationTimestamp = types.StringNull()
		} else {
			// Harmonize the timestamp format
			// Eg. "2027-01-02T03:04:05.000Z" = "2027-01-02T03:04:05Z"
			expirationTimestamp, err := time.Parse(time.RFC3339, *credential.Expires)
			if err != nil {
				return foundCredential, fmt.Errorf("unable to parse payload expiration timestamp '%v': %w", *credential.Expires, err)
			}
			model.ExpirationTimestamp = types.StringValue(expirationTimestamp.Format(time.RFC3339))
		}
		break
	}

	return foundCredential, nil
}