package postgresflexalpha

import (
	"context"
	"errors"
	"fmt"
	"net/http"
	"regexp"
	"strconv"
	"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/int64planmodifier"
	"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/mhenselin/terraform-provider-stackitprivatepreview/pkg/postgresflexalpha"
	"github.com/mhenselin/terraform-provider-stackitprivatepreview/stackit/internal/conversion"
	"github.com/mhenselin/terraform-provider-stackitprivatepreview/stackit/internal/core"
	postgresflexUtils "github.com/mhenselin/terraform-provider-stackitprivatepreview/stackit/internal/services/postgresflexalpha/utils"
	"github.com/mhenselin/terraform-provider-stackitprivatepreview/stackit/internal/utils"
	"github.com/mhenselin/terraform-provider-stackitprivatepreview/stackit/internal/validate"
	"github.com/stackitcloud/stackit-sdk-go/core/oapierror"
)

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

type Model struct {
	Id         types.String `tfsdk:"id"` // needed by TF
	DatabaseId types.Int64  `tfsdk:"database_id"`
	InstanceId types.String `tfsdk:"instance_id"`
	ProjectId  types.String `tfsdk:"project_id"`
	Name       types.String `tfsdk:"name"`
	Owner      types.String `tfsdk:"owner"`
	Region     types.String `tfsdk:"region"`
}

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

// databaseResource is the resource implementation.
type databaseResource struct {
	client       *postgresflexalpha.APIClient
	providerData core.ProviderData
}

// ModifyPlan implements resource.ResourceWithModifyPlan.
// Use the modifier to set the effective region in the current plan.
func (r *databaseResource) ModifyPlan(
	ctx context.Context,
	req resource.ModifyPlanRequest,
	resp *resource.ModifyPlanResponse,
) { // nolint:gocritic // function signature required by Terraform
	var configModel Model
	// skip initial empty configuration to avoid follow-up errors
	if req.Config.Raw.IsNull() {
		return
	}
	resp.Diagnostics.Append(req.Config.Get(ctx, &configModel)...)
	if resp.Diagnostics.HasError() {
		return
	}

	var planModel Model
	resp.Diagnostics.Append(req.Plan.Get(ctx, &planModel)...)
	if resp.Diagnostics.HasError() {
		return
	}

	utils.AdaptRegion(ctx, configModel.Region, &planModel.Region, r.providerData.GetRegion(), resp)
	if resp.Diagnostics.HasError() {
		return
	}

	resp.Diagnostics.Append(resp.Plan.Set(ctx, planModel)...)
	if resp.Diagnostics.HasError() {
		return
	}
}

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

// Configure adds the provider configured client to the resource.
func (r *databaseResource) Configure(
	ctx context.Context,
	req resource.ConfigureRequest,
	resp *resource.ConfigureResponse,
) {
	var ok bool
	r.providerData, ok = conversion.ParseProviderData(ctx, req.ProviderData, &resp.Diagnostics)
	if !ok {
		return
	}

	apiClient := postgresflexUtils.ConfigureClient(ctx, &r.providerData, &resp.Diagnostics)
	if resp.Diagnostics.HasError() {
		return
	}
	r.client = apiClient
	tflog.Info(ctx, "Postgres Flex database client configured")
}

// Schema defines the schema for the resource.
func (r *databaseResource) Schema(_ context.Context, _ resource.SchemaRequest, resp *resource.SchemaResponse) {
	descriptions := map[string]string{
		"main":        "Postgres Flex database resource schema. Must have a `region` specified in the provider configuration.",
		"id":          "Terraform's internal resource ID. It is structured as \"`project_id`,`region`,`instance_id`,`database_id`\".",
		"database_id": "Database ID.",
		"instance_id": "ID of the Postgres Flex instance.",
		"project_id":  "STACKIT project ID to which the instance is associated.",
		"name":        "Database name.",
		"owner":       "Username of the database owner.",
		"region":      "The resource region. If not defined, the provider region is used.",
	}

	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(),
				},
			},
			"database_id": schema.Int64Attribute{
				Description: descriptions["database_id"],
				Computed:    true,
				PlanModifiers: []planmodifier.Int64{
					int64planmodifier.UseStateForUnknown(),
				},
				Validators: []validator.Int64{},
			},
			"instance_id": schema.StringAttribute{
				Description: descriptions["instance_id"],
				Required:    true,
				PlanModifiers: []planmodifier.String{
					stringplanmodifier.RequiresReplace(),
					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{
				Description:   descriptions["name"],
				Required:      true,
				PlanModifiers: []planmodifier.String{},
				Validators: []validator.String{
					stringvalidator.RegexMatches(
						regexp.MustCompile("^[a-z]([a-z0-9]*)?$"),
						"must start with a letter, must have lower case letters or numbers",
					),
				},
			},
			"owner": schema.StringAttribute{
				Description:   descriptions["owner"],
				Required:      true,
				PlanModifiers: []planmodifier.String{},
			},
			"region": schema.StringAttribute{
				Optional: true,
				// must be computed to allow for storing the override value from the provider
				Computed:    true,
				Description: descriptions["region"],
				PlanModifiers: []planmodifier.String{
					stringplanmodifier.RequiresReplace(),
				},
			},
		},
	}
}

// Create creates the resource and sets the initial Terraform state.
func (r *databaseResource) 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
	}

	ctx = core.InitProviderContext(ctx)

	projectId := model.ProjectId.ValueString()
	region := model.Region.ValueString()
	instanceId := model.InstanceId.ValueString()
	ctx = tflog.SetField(ctx, "project_id", projectId)
	ctx = tflog.SetField(ctx, "instance_id", instanceId)
	ctx = tflog.SetField(ctx, "region", region)

	// Generate API request body from model
	payload, err := toCreatePayload(&model)
	if err != nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"Error creating database",
			fmt.Sprintf("Creating API payload: %v", err),
		)
		return
	}
	// Create new database
	databaseResp, err := r.client.CreateDatabaseRequest(
		ctx,
		projectId,
		region,
		instanceId,
	).CreateDatabaseRequestPayload(*payload).Execute()
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error creating database", fmt.Sprintf("Calling API: %v", err))
		return
	}

	ctx = core.LogResponse(ctx)

	if databaseResp == nil || databaseResp.Id == nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"Error creating database",
			"API didn't return database Id. A database might have been created",
		)
		return
	}
	databaseId := *databaseResp.Id
	ctx = tflog.SetField(ctx, "database_id", databaseId)

	database, err := getDatabaseById(ctx, r.client, projectId, region, instanceId, databaseId)
	if err != nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"Error creating database",
			fmt.Sprintf("Getting database details after creation: %v", err),
		)
		return
	}

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

// Read refreshes the Terraform state with the latest data.
func (r *databaseResource) 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
	}

	ctx = core.InitProviderContext(ctx)

	projectId := model.ProjectId.ValueString()
	instanceId := model.InstanceId.ValueString()
	databaseId := model.DatabaseId.ValueInt64()
	region := r.providerData.GetRegionWithOverride(model.Region)
	ctx = tflog.SetField(ctx, "project_id", projectId)
	ctx = tflog.SetField(ctx, "instance_id", instanceId)
	ctx = tflog.SetField(ctx, "database_id", databaseId)
	ctx = tflog.SetField(ctx, "region", region)

	databaseResp, err := getDatabaseById(ctx, r.client, projectId, region, instanceId, databaseId)
	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) || errors.Is(err, errDatabaseNotFound) {
			resp.State.RemoveResource(ctx)
			return
		}
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error reading database", fmt.Sprintf("Calling API: %v", err))
		return
	}

	ctx = core.LogResponse(ctx)

	// Map response body to schema
	err = mapFields(databaseResp, &model, region)
	if err != nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"Error reading database",
			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, "Postgres Flex database read")
}

// Update updates the resource and sets the updated Terraform state on success.
func (r *databaseResource) Update(
	ctx context.Context,
	req resource.UpdateRequest,
	resp *resource.UpdateResponse,
) {
	var model Model
	diags := req.Plan.Get(ctx, &model)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}

	ctx = core.InitProviderContext(ctx)

	projectId := model.ProjectId.ValueString()
	instanceId := model.InstanceId.ValueString()
	databaseId := model.DatabaseId.ValueInt64()
	region := model.Region.ValueString()
	ctx = tflog.SetField(ctx, "project_id", projectId)
	ctx = tflog.SetField(ctx, "instance_id", instanceId)
	ctx = tflog.SetField(ctx, "database_id", databaseId)
	ctx = tflog.SetField(ctx, "region", region)

	// Retrieve values from state
	var stateModel Model
	diags = req.State.Get(ctx, &stateModel)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}

	modified := false
	var payload postgresflexalpha.UpdateDatabasePartiallyRequestPayload
	if stateModel.Name != model.Name {
		payload.Name = model.Name.ValueStringPointer()
		modified = true
	}

	if stateModel.Owner != model.Owner {
		payload.Owner = model.Owner.ValueStringPointer()
		modified = true
	}

	if !modified {
		tflog.Info(ctx, "no modification detected")
		return
	}

	// Update existing database
	res, err := r.client.UpdateDatabasePartiallyRequest(
		ctx,
		projectId,
		region,
		instanceId,
		databaseId,
	).UpdateDatabasePartiallyRequestPayload(payload).Execute()
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "error updating database", err.Error())
		return
	}

	ctx = core.LogResponse(ctx)

	// Map response body to schema
	err = mapFieldsUpdatePartially(res, &model, region)
	if err != nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"Error updating database",
			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, "Postgres Flex database updated")
}

// Delete deletes the resource and removes the Terraform state on success.
func (r *databaseResource) 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
	}

	ctx = core.InitProviderContext(ctx)

	projectId := model.ProjectId.ValueString()
	instanceId := model.InstanceId.ValueString()
	databaseId := model.DatabaseId.ValueInt64()
	region := model.Region.ValueString()
	ctx = tflog.SetField(ctx, "project_id", projectId)
	ctx = tflog.SetField(ctx, "instance_id", instanceId)
	ctx = tflog.SetField(ctx, "database_id", databaseId)
	ctx = tflog.SetField(ctx, "region", region)

	// Delete existing record set
	err := r.client.DeleteDatabaseRequestExecute(ctx, projectId, region, instanceId, databaseId)
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error deleting database", fmt.Sprintf("Calling API: %v", err))
	}

	ctx = core.LogResponse(ctx)

	tflog.Info(ctx, "Postgres Flex database deleted")
}

// ImportState imports a resource into the Terraform state on success.
// The expected format of the resource import identifier is: project_id,zone_id,record_set_id
func (r *databaseResource) ImportState(
	ctx context.Context,
	req resource.ImportStateRequest,
	resp *resource.ImportStateResponse,
) {
	idParts := strings.Split(req.ID, core.Separator)
	if len(idParts) != 4 || idParts[0] == "" || idParts[1] == "" || idParts[2] == "" || idParts[3] == "" {
		core.LogAndAddError(
			ctx, &resp.Diagnostics,
			"Error importing database",
			fmt.Sprintf(
				"Expected import identifier with format [project_id],[region],[instance_id],[database_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("region"), idParts[1])...)
	resp.Diagnostics.Append(resp.State.SetAttribute(ctx, path.Root("instance_id"), idParts[2])...)
	resp.Diagnostics.Append(resp.State.SetAttribute(ctx, path.Root("database_id"), idParts[3])...)
	core.LogAndAddWarning(
		ctx,
		&resp.Diagnostics,
		"Postgresflex database imported with empty password",
		"The database password is not imported as it is only available upon creation of a new database. The password field will be empty.",
	)
	tflog.Info(ctx, "Postgres Flex database state imported")
}

func mapFields(resp *postgresflexalpha.ListDatabase, model *Model, region string) error {
	if resp == nil {
		return fmt.Errorf("response is nil")
	}
	if resp.Id == nil || *resp.Id == 0 {
		return fmt.Errorf("id not present")
	}
	if model == nil {
		return fmt.Errorf("model input is nil")
	}

	var databaseId int64
	if model.DatabaseId.ValueInt64() != 0 {
		databaseId = model.DatabaseId.ValueInt64()
	} else if resp.Id != nil {
		databaseId = *resp.Id
	} else {
		return fmt.Errorf("database id not present")
	}
	model.Id = utils.BuildInternalTerraformId(
		model.ProjectId.ValueString(), region, model.InstanceId.ValueString(), strconv.FormatInt(databaseId, 10),
	)
	model.DatabaseId = types.Int64Value(databaseId)
	model.Name = types.StringPointerValue(resp.Name)
	model.Region = types.StringValue(region)
	model.Owner = types.StringPointerValue(cleanString(resp.Owner))
	return nil
}

func mapFieldsUpdatePartially(
	res *postgresflexalpha.UpdateDatabasePartiallyResponse,
	model *Model,
	region string,
) error {
	if res == nil {
		return fmt.Errorf("response is nil")
	}
	return mapFields(res.Database, model, region)
}

func cleanString(s *string) *string {
	if s == nil {
		return nil
	}
	res := strings.Trim(*s, "\"")
	return &res
}

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

	return &postgresflexalpha.CreateDatabaseRequestPayload{
		Name:  model.Name.ValueStringPointer(),
		Owner: model.Owner.ValueStringPointer(),
	}, nil
}

var errDatabaseNotFound = errors.New("database not found")