package postgresflexalpha

import (
	"context"
	_ "embed"
	"errors"
	"fmt"
	"math"
	"strconv"
	"strings"
	"time"

	"github.com/hashicorp/terraform-plugin-framework/path"
	"github.com/hashicorp/terraform-plugin-framework/resource"
	"github.com/hashicorp/terraform-plugin-framework/resource/identityschema"
	"github.com/hashicorp/terraform-plugin-framework/types"
	"github.com/hashicorp/terraform-plugin-log/tflog"
	"tf-provider.git.onstackit.cloud/stackit-dev-tools/terraform-provider-stackitprivatepreview/pkg_gen/postgresflexalpha"
	"tf-provider.git.onstackit.cloud/stackit-dev-tools/terraform-provider-stackitprivatepreview/stackit/internal/conversion"
	"tf-provider.git.onstackit.cloud/stackit-dev-tools/terraform-provider-stackitprivatepreview/stackit/internal/core"
	postgresflexalpha2 "tf-provider.git.onstackit.cloud/stackit-dev-tools/terraform-provider-stackitprivatepreview/stackit/internal/services/postgresflexalpha/database/resources_gen"
	postgresflexUtils "tf-provider.git.onstackit.cloud/stackit-dev-tools/terraform-provider-stackitprivatepreview/stackit/internal/services/postgresflexalpha/utils"
	"tf-provider.git.onstackit.cloud/stackit-dev-tools/terraform-provider-stackitprivatepreview/stackit/internal/utils"
	postgresflexalpha3 "tf-provider.git.onstackit.cloud/stackit-dev-tools/terraform-provider-stackitprivatepreview/stackit/internal/wait/postgresflexalpha"
)

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

	// Define errors
	errDatabaseNotFound = errors.New("database not found")

	// Error message constants
	extractErrorSummary = "extracting failed"
	extractErrorMessage = "Extracting identity data: %v"
)

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

// resourceModel describes the resource data model.
type resourceModel = postgresflexalpha2.DatabaseModel

// DatabaseResourceIdentityModel describes the resource's identity attributes.
type DatabaseResourceIdentityModel struct {
	ProjectID  types.String `tfsdk:"project_id"`
	Region     types.String `tfsdk:"region"`
	InstanceID types.String `tfsdk:"instance_id"`
	DatabaseID types.Int64  `tfsdk:"database_id"`
}

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

// ModifyPlan adjusts the plan to set the correct region.
func (r *databaseResource) ModifyPlan(
	ctx context.Context,
	req resource.ModifyPlanRequest,
	resp *resource.ModifyPlanResponse,
) { // nolint:gocritic // function signature required by Terraform
	var configModel resourceModel
	// 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 resourceModel
	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")
}

//go:embed planModifiers.yaml
var modifiersFileByte []byte

// Schema defines the schema for the resource.
func (r *databaseResource) Schema(ctx context.Context, _ resource.SchemaRequest, resp *resource.SchemaResponse) {
	s := postgresflexalpha2.DatabaseResourceSchema(ctx)

	fields, err := utils.ReadModifiersConfig(modifiersFileByte)
	if err != nil {
		resp.Diagnostics.AddError("error during read modifiers config file", err.Error())
		return
	}

	err = utils.AddPlanModifiersToResourceSchema(fields, &s)
	if err != nil {
		resp.Diagnostics.AddError("error adding plan modifiers", err.Error())
		return
	}
	resp.Schema = s
}

// IdentitySchema defines the schema for the resource's identity attributes.
func (r *databaseResource) IdentitySchema(
	_ context.Context,
	_ resource.IdentitySchemaRequest,
	response *resource.IdentitySchemaResponse,
) {
	response.IdentitySchema = identityschema.Schema{
		Attributes: map[string]identityschema.Attribute{
			"project_id": identityschema.StringAttribute{
				RequiredForImport: true,
			},
			"region": identityschema.StringAttribute{
				RequiredForImport: true,
			},
			"instance_id": identityschema.StringAttribute{
				RequiredForImport: true,
			},
			"database_id": identityschema.Int64Attribute{
				RequiredForImport: true,
			},
		},
	}
}

// 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 resourceModel
	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.InstanceId.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
	}

	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)
	ctx = core.LogResponse(ctx)

	// Save identity into Terraform state
	identity := DatabaseResourceIdentityModel{
		ProjectID:  types.StringValue(projectId),
		Region:     types.StringValue(region),
		InstanceID: types.StringValue(instanceId),
		DatabaseID: types.Int64Value(databaseId),
	}
	resp.Diagnostics.Append(resp.Identity.Set(ctx, identity)...)
	if resp.Diagnostics.HasError() {
		return
	}

	database, err := postgresflexalpha3.GetDatabaseByIdWaitHandler(ctx, r.client, projectId, region, instanceId, databaseId).
		SetTimeout(15 * time.Minute).
		SetSleepBeforeWait(15 * time.Second).
		WaitWithContext(ctx)
	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 = mapResourceFields(database, &model)
	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
	resp.Diagnostics.Append(resp.State.Set(ctx, model)...)
	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 resourceModel
	diags := req.State.Get(ctx, &model)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}

	// Read identity data
	var identityData DatabaseResourceIdentityModel
	resp.Diagnostics.Append(req.Identity.Get(ctx, &identityData)...)
	if resp.Diagnostics.HasError() {
		return
	}

	ctx = core.InitProviderContext(ctx)

	projectId, instanceId, region, databaseId, errExt := r.extractIdentityData(model, identityData)
	if errExt != nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			extractErrorSummary,
			fmt.Sprintf(extractErrorMessage, errExt),
		)
	}

	ctx = tflog.SetField(ctx, "project_id", projectId)
	ctx = tflog.SetField(ctx, "instance_id", instanceId)
	ctx = tflog.SetField(ctx, "region", region)
	ctx = tflog.SetField(ctx, "database_id", databaseId)

	databaseResp, err := postgresflexalpha3.GetDatabaseByIdWaitHandler(ctx, r.client, projectId, region, instanceId, databaseId).
		SetTimeout(15 * time.Minute).
		SetSleepBeforeWait(15 * time.Second).
		WaitWithContext(ctx)
	if err != nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"Error creating database",
			fmt.Sprintf("Getting database details after creation: %v", err),
		)
		return
	}

	ctx = core.LogResponse(ctx)

	// Map response body to schema
	err = mapResourceFields(databaseResp, &model)
	if err != nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"Error reading database",
			fmt.Sprintf("Processing API payload: %v", err),
		)
		return
	}

	// Save identity into Terraform state
	identity := DatabaseResourceIdentityModel{
		ProjectID:  types.StringValue(projectId),
		Region:     types.StringValue(region),
		InstanceID: types.StringValue(instanceId),
		DatabaseID: types.Int64Value(databaseId),
	}
	resp.Diagnostics.Append(resp.Identity.Set(ctx, identity)...)
	if resp.Diagnostics.HasError() {
		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 resourceModel
	diags := req.Plan.Get(ctx, &model)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}

	// Read identity data
	var identityData DatabaseResourceIdentityModel
	resp.Diagnostics.Append(req.Identity.Get(ctx, &identityData)...)
	if resp.Diagnostics.HasError() {
		return
	}

	ctx = core.InitProviderContext(ctx)

	projectId, instanceId, region, databaseId64, errExt := r.extractIdentityData(model, identityData)
	if errExt != nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			extractErrorSummary,
			fmt.Sprintf(extractErrorMessage, errExt),
		)
	}

	if databaseId64 > math.MaxInt32 {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error in type conversion", "int value too large (databaseId)")
		return
	}
	databaseId := int32(databaseId64)

	ctx = tflog.SetField(ctx, "project_id", projectId)
	ctx = tflog.SetField(ctx, "instance_id", instanceId)
	ctx = tflog.SetField(ctx, "region", region)
	ctx = tflog.SetField(ctx, "database_id", databaseId)

	// Retrieve values from state
	var stateModel resourceModel
	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
	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)

	databaseResp, err := postgresflexalpha3.GetDatabaseByIdWaitHandler(ctx, r.client, projectId, region, instanceId, databaseId64).
		SetTimeout(15 * time.Minute).
		SetSleepBeforeWait(15 * time.Second).
		WaitWithContext(ctx)
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "error updating database", err.Error())
		return
	}

	ctx = core.LogResponse(ctx)

	// Map response body to schema
	err = mapResourceFields(databaseResp, &model)
	if err != nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"Error reading database",
			fmt.Sprintf("Processing API payload: %v", err),
		)
		return
	}

	// Save identity into Terraform state
	identity := DatabaseResourceIdentityModel{
		ProjectID:  types.StringValue(projectId),
		Region:     types.StringValue(region),
		InstanceID: types.StringValue(instanceId),
		DatabaseID: types.Int64Value(databaseId64),
	}
	resp.Diagnostics.Append(resp.Identity.Set(ctx, identity)...)
	if resp.Diagnostics.HasError() {
		return
	}

	// Set state to fully populated data
	resp.Diagnostics.Append(resp.State.Set(ctx, &model)...)
	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 resourceModel
	diags := req.State.Get(ctx, &model)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}

	// Read identity data
	var identityData DatabaseResourceIdentityModel
	resp.Diagnostics.Append(req.Identity.Get(ctx, &identityData)...)
	if resp.Diagnostics.HasError() {
		return
	}

	ctx = core.InitProviderContext(ctx)

	projectId, instanceId, region, databaseId64, errExt := r.extractIdentityData(model, identityData)
	if errExt != nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			extractErrorSummary,
			fmt.Sprintf(extractErrorMessage, errExt),
		)
	}

	if databaseId64 > math.MaxInt32 {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error in type conversion", "int value too large (databaseId)")
		return
	}
	databaseId := int32(databaseId64)
	ctx = tflog.SetField(ctx, "project_id", projectId)
	ctx = tflog.SetField(ctx, "instance_id", instanceId)
	ctx = tflog.SetField(ctx, "region", region)
	ctx = tflog.SetField(ctx, "database_id", databaseId)

	// 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 import identifier format is: [project_id],[region],[instance_id],[database_id]
func (r *databaseResource) ImportState(
	ctx context.Context,
	req resource.ImportStateRequest,
	resp *resource.ImportStateResponse,
) {

	ctx = core.InitProviderContext(ctx)

	if req.ID != "" {

		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
		}

		databaseId, err := strconv.ParseInt(idParts[3], 10, 64)
		if err != nil {
			core.LogAndAddError(
				ctx,
				&resp.Diagnostics,
				"Error importing database",
				fmt.Sprintf("Invalid database_id format: %q. It must be a valid integer.", idParts[3]),
			)
			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"), databaseId)...)

		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")

		return
	}

	// If no ID is provided, attempt to read identity attributes from the import configuration
	var identityData DatabaseResourceIdentityModel
	resp.Diagnostics.Append(req.Identity.Get(ctx, &identityData)...)
	if resp.Diagnostics.HasError() {
		return
	}

	projectId := identityData.ProjectID.ValueString()
	region := identityData.Region.ValueString()
	instanceId := identityData.InstanceID.ValueString()
	databaseId := identityData.DatabaseID.ValueInt64()

	resp.Diagnostics.Append(resp.State.SetAttribute(ctx, path.Root("project_id"), projectId)...)
	resp.Diagnostics.Append(resp.State.SetAttribute(ctx, path.Root("region"), region)...)
	resp.Diagnostics.Append(resp.State.SetAttribute(ctx, path.Root("instance_id"), instanceId)...)
	resp.Diagnostics.Append(resp.State.SetAttribute(ctx, path.Root("database_id"), databaseId)...)

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

// extractIdentityData extracts essential identifiers from the resource model, falling back to the identity model.
func (r *databaseResource) extractIdentityData(
	model resourceModel,
	identity DatabaseResourceIdentityModel,
) (projectId, region, instanceId string, databaseId int64, err error) {
	if !model.DatabaseId.IsNull() && !model.DatabaseId.IsUnknown() {
		databaseId = model.DatabaseId.ValueInt64()
	} else {
		if identity.DatabaseID.IsNull() || identity.DatabaseID.IsUnknown() {
			return "", "", "", 0, fmt.Errorf("database_id not found in config")
		}
		databaseId = identity.DatabaseID.ValueInt64()
	}

	if !model.ProjectId.IsNull() && !model.ProjectId.IsUnknown() {
		projectId = model.ProjectId.ValueString()
	} else {
		if identity.ProjectID.IsNull() || identity.ProjectID.IsUnknown() {
			return "", "", "", 0, fmt.Errorf("project_id not found in config")
		}
		projectId = identity.ProjectID.ValueString()
	}

	if !model.Region.IsNull() && !model.Region.IsUnknown() {
		region = r.providerData.GetRegionWithOverride(model.Region)
	} else {
		if identity.Region.IsNull() || identity.Region.IsUnknown() {
			return "", "", "", 0, fmt.Errorf("region not found in config")
		}
		region = r.providerData.GetRegionWithOverride(identity.Region)
	}

	if !model.InstanceId.IsNull() && !model.InstanceId.IsUnknown() {
		instanceId = model.InstanceId.ValueString()
	} else {
		if identity.InstanceID.IsNull() || identity.InstanceID.IsUnknown() {
			return "", "", "", 0, fmt.Errorf("instance_id not found in config")
		}
		instanceId = identity.InstanceID.ValueString()
	}
	return projectId, region, instanceId, databaseId, nil
}