package postgresflexalpha

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

	"github.com/hashicorp/terraform-plugin-framework/diag"
	"github.com/hashicorp/terraform-plugin-framework/resource/identityschema"

	postgresflex "tf-provider.git.onstackit.cloud/stackit-dev-tools/terraform-provider-stackitprivatepreview/pkg_gen/postgresflexalpha"
	postgresflexalpha "tf-provider.git.onstackit.cloud/stackit-dev-tools/terraform-provider-stackitprivatepreview/stackit/internal/services/postgresflexalpha/user/resources_gen"
	postgresflexUtils "tf-provider.git.onstackit.cloud/stackit-dev-tools/terraform-provider-stackitprivatepreview/stackit/internal/services/postgresflexalpha/utils"
	postgresflexalphaWait "tf-provider.git.onstackit.cloud/stackit-dev-tools/terraform-provider-stackitprivatepreview/stackit/internal/wait/postgresflexalpha"

	"github.com/hashicorp/terraform-plugin-framework/path"
	"github.com/hashicorp/terraform-plugin-framework/resource"
	"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/stackit/internal/conversion"
	"tf-provider.git.onstackit.cloud/stackit-dev-tools/terraform-provider-stackitprivatepreview/stackit/internal/core"
	"tf-provider.git.onstackit.cloud/stackit-dev-tools/terraform-provider-stackitprivatepreview/stackit/internal/utils"
)

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

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

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

// resourceModel represents the Terraform resource state for a PostgreSQL Flex user.
type resourceModel = postgresflexalpha.UserModel

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

// userResource implements the resource handling for a PostgreSQL Flex user.
type userResource struct {
	client       *postgresflex.APIClient
	providerData core.ProviderData
}

// ModifyPlan implements resource.ResourceWithModifyPlan.
// Use the modifier to set the effective region in the current plan.
func (r *userResource) 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 *userResource) Metadata(_ context.Context, req resource.MetadataRequest, resp *resource.MetadataResponse) {
	resp.TypeName = req.ProviderTypeName + "_postgresflexalpha_user"
}

// Configure adds the provider configured client to the resource.
func (r *userResource) 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 user client configured")
}

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

// Schema defines the schema for the resource.
func (r *userResource) Schema(ctx context.Context, _ resource.SchemaRequest, resp *resource.SchemaResponse) {
	s := postgresflexalpha.UserResourceSchema(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
}

func (r *userResource) ValidateConfig(
	ctx context.Context,
	req resource.ValidateConfigRequest,
	resp *resource.ValidateConfigResponse,
) {
	var data resourceModel

	resp.Diagnostics.Append(req.Config.Get(ctx, &data)...)
	if resp.Diagnostics.HasError() {
		return
	}

	var roles []string
	diags := data.Roles.ElementsAs(ctx, &roles, false)
	resp.Diagnostics.Append(diags...)
	if diags.HasError() {
		return
	}

	var resRoles []string
	for _, role := range roles {
		if slices.Contains(resRoles, role) {
			resp.Diagnostics.AddAttributeError(
				path.Root("roles"),
				"Attribute Configuration Error",
				"defined roles MUST NOT contain duplicates",
			)
			return
		}
		resRoles = append(resRoles, role)
	}
}

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

	arg := &clientArg{
		projectId:  model.ProjectId.ValueString(),
		instanceId: model.InstanceId.ValueString(),
		region:     r.providerData.GetRegionWithOverride(model.Region),
	}

	ctx = r.setTFLogFields(ctx, arg)

	var roles = r.expandRoles(ctx, model.Roles, &resp.Diagnostics)
	if resp.Diagnostics.HasError() {
		return
	}

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

	// Create new user
	userResp, err := r.client.CreateUserRequest(
		ctx,
		arg.projectId,
		arg.region,
		arg.instanceId,
	).CreateUserRequestPayload(*payload).Execute()
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error creating user", fmt.Sprintf("Calling API: %v", err))
		return
	}

	id, ok := userResp.GetIdOk()
	if !ok || id == 0 {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"Error creating user",
			"API didn't return user Id. A user might have been created",
		)
		return
	}
	arg.userId = id

	ctx = tflog.SetField(ctx, "user_id", id)

	ctx = core.LogResponse(ctx)

	// Set data returned by API in identity
	identity := UserResourceIdentityModel{
		ProjectID:  types.StringValue(arg.projectId),
		Region:     types.StringValue(arg.region),
		InstanceID: types.StringValue(arg.instanceId),
		UserID:     types.Int64Value(id),
	}
	resp.Diagnostics.Append(resp.Identity.Set(ctx, identity)...)
	if resp.Diagnostics.HasError() {
		return
	}

	model.Id = types.Int64Value(id)
	model.UserId = types.Int64Value(id)
	model.Password = types.StringValue(userResp.GetPassword())
	model.Status = types.StringValue(userResp.GetStatus())

	waitResp, err := postgresflexalphaWait.GetUserByIdWaitHandler(
		ctx,
		r.client,
		arg.projectId,
		arg.instanceId,
		arg.region,
		id,
	).SetSleepBeforeWait(
		10 * time.Second,
	).SetTimeout(
		15 * time.Minute,
	).WaitWithContext(ctx)

	if err != nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"create user",
			fmt.Sprintf("Instance creation waiting: %v", err),
		)
		return
	}

	if waitResp.Id == nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"create user",
			"Instance creation waiting: returned id is nil",
		)
		return
	}
	if waitResp.Id == nil || *waitResp.Id != id {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"create user",
			fmt.Sprintf(
				"Instance creation waiting: returned id is wrong: %+v - %+v",
				waitResp.Id,
				id,
			),
		)
		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 user created")
}

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

	ctx = core.InitProviderContext(ctx)

	arg := &clientArg{
		projectId:  model.ProjectId.ValueString(),
		instanceId: model.InstanceId.ValueString(),
		region:     r.providerData.GetRegionWithOverride(model.Region),
	}

	ctx = r.setTFLogFields(ctx, arg)

	ctx = core.InitProviderContext(ctx)

	// Read resource state
	waitResp, err := postgresflexalphaWait.GetUserByIdWaitHandler(
		ctx,
		r.client,
		arg.projectId,
		arg.instanceId,
		arg.region,
		model.UserId.ValueInt64(),
	).SetSleepBeforeWait(
		10 * time.Second,
	).SetTimeout(
		15 * time.Minute,
	).WaitWithContext(ctx)

	if err != nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"read user",
			fmt.Sprintf("Instance creation waiting: %v", err),
		)
		return
	}

	if waitResp.Id == nil || *waitResp.Id != model.UserId.ValueInt64() {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"read user",
			"Instance creation waiting: returned id is nil or wrong",
		)
		return
	}
	arg.userId = *waitResp.Id

	ctx = core.LogResponse(ctx)

	// Set data returned by API in identity
	identity := UserResourceIdentityModel{
		ProjectID:  types.StringValue(arg.projectId),
		Region:     types.StringValue(arg.region),
		InstanceID: types.StringValue(arg.instanceId),
		UserID:     types.Int64Value(arg.userId),
	}
	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 user read")
}

// Update updates the resource and sets the updated Terraform state on success.
func (r *userResource) Update(
	ctx context.Context,
	req resource.UpdateRequest,
	resp *resource.UpdateResponse,
) { // 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)

	arg := &clientArg{
		projectId:  model.ProjectId.ValueString(),
		instanceId: model.InstanceId.ValueString(),
		region:     r.providerData.GetRegionWithOverride(model.Region),
	}

	ctx = r.setTFLogFields(ctx, arg)
	ctx = core.InitProviderContext(ctx)

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

	var roles = r.expandRoles(ctx, model.Roles, &resp.Diagnostics)
	if resp.Diagnostics.HasError() {
		return
	}

	// Generate API request body from model
	payload, err := toUpdatePayload(&model, &roles)
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error updating user", fmt.Sprintf("Updating API payload: %v", err))
		return
	}

	userId64 := arg.userId
	if userId64 > math.MaxInt32 {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error in type conversion", "int value too large (userId)")
		return
	}
	userId := int32(userId64) // nolint:gosec // check is performed above

	// Update existing instance
	err = r.client.UpdateUserRequest(
		ctx,
		arg.projectId,
		arg.region,
		arg.instanceId,
		userId,
	).UpdateUserRequestPayload(*payload).Execute()
	if err != nil {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error updating user", err.Error())
		return
	}

	ctx = core.LogResponse(ctx)

	// Set data returned by API in identity
	identity := UserResourceIdentityModel{
		ProjectID:  types.StringValue(arg.projectId),
		Region:     types.StringValue(arg.region),
		InstanceID: types.StringValue(arg.instanceId),
		UserID:     types.Int64Value(userId64),
	}
	resp.Diagnostics.Append(resp.Identity.Set(ctx, identity)...)
	if resp.Diagnostics.HasError() {
		return
	}

	// Verify update
	waitResp, err := postgresflexalphaWait.GetUserByIdWaitHandler(
		ctx,
		r.client,
		arg.projectId,
		arg.instanceId,
		arg.region,
		model.UserId.ValueInt64(),
	).SetSleepBeforeWait(
		10 * time.Second,
	).SetTimeout(
		15 * time.Minute,
	).WaitWithContext(ctx)

	if err != nil {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"read user",
			fmt.Sprintf("user update waiting: %v", err),
		)
		return
	}

	if waitResp.Id == nil || *waitResp.Id != model.UserId.ValueInt64() {
		core.LogAndAddError(
			ctx,
			&resp.Diagnostics,
			"update user",
			"User creation waiting: returned id is nil or wrong",
		)
		return
	}
	arg.userId = *waitResp.Id

	// Set state to fully populated data
	diags = resp.State.Set(ctx, stateModel)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}
	tflog.Info(ctx, "Postgres Flex user updated")
}

// Delete deletes the resource and removes the Terraform state on success.
func (r *userResource) 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 UserResourceIdentityModel
	resp.Diagnostics.Append(req.Identity.Get(ctx, &identityData)...)
	if resp.Diagnostics.HasError() {
		return
	}

	ctx = core.InitProviderContext(ctx)

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

	ctx = r.setTFLogFields(ctx, arg)
	ctx = core.InitProviderContext(ctx)

	userId64 := arg.userId
	if userId64 > math.MaxInt32 {
		core.LogAndAddError(ctx, &resp.Diagnostics, "Error in type conversion", "int value too large (userId)")
		return
	}
	userId := int32(userId64) // nolint:gosec // check is performed above

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

	ctx = core.LogResponse(ctx)

	// TODO: Verify deletion
	// exists, err := r.getUserResource(ctx, &model, arg)
	// if err != nil {
	//	core.LogAndAddError(ctx, &resp.Diagnostics, "Error deleting user", fmt.Sprintf("Calling API: %v", err))
	//	return
	//}
	// if exists {
	//	core.LogAndAddError(
	//		ctx, &resp.Diagnostics, "Error deleting user",
	//		fmt.Sprintf("User ID '%v' resource still exists after deletion", model.UserId.ValueInt64()),
	//	)
	//	return
	//}

	resp.State.RemoveResource(ctx)

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

// IdentitySchema defines the fields that are required to uniquely identify a resource.
func (r *userResource) 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,
			},
			"user_id": identityschema.Int64Attribute{
				RequiredForImport: true,
			},
		},
	}
}

// clientArg holds the arguments for API calls.
type clientArg struct {
	projectId  string
	instanceId string
	region     string
	userId     int64
}

// 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 *userResource) 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 user",
				fmt.Sprintf(
					"Expected import identifier with format [project_id],[region],[instance_id],[user_id], got %q",
					req.ID,
				),
			)
			return
		}

		userId, err := strconv.ParseInt(idParts[3], 10, 64)
		if err != nil {
			core.LogAndAddError(
				ctx,
				&resp.Diagnostics,
				"Error importing user",
				fmt.Sprintf("Invalid user_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("user_id"), userId)...)

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

		return
	}

	// If no ID is provided, attempt to read identity attributes from the import configuration
	var identityData UserResourceIdentityModel
	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()
	userId := identityData.UserID.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("user_id"), userId)...)

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

// extractIdentityData extracts essential identifiers from the resource model, falling back to the identity model.
func (r *userResource) extractIdentityData(
	model resourceModel,
	identity UserResourceIdentityModel,
) (*clientArg, error) {
	var projectId, region, instanceId string
	var userId int64

	if !model.UserId.IsNull() && !model.UserId.IsUnknown() {
		userId = model.UserId.ValueInt64()
	} else {
		if identity.UserID.IsNull() || identity.UserID.IsUnknown() {
			return nil, fmt.Errorf("user_id not found in config")
		}
		userId = identity.UserID.ValueInt64()
	}

	if !model.ProjectId.IsNull() && !model.ProjectId.IsUnknown() {
		projectId = model.ProjectId.ValueString()
	} else {
		if identity.ProjectID.IsNull() || identity.ProjectID.IsUnknown() {
			return nil, 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 nil, 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 nil, fmt.Errorf("instance_id not found in config")
		}
		instanceId = identity.InstanceID.ValueString()
	}
	return &clientArg{
		projectId:  projectId,
		instanceId: instanceId,
		region:     region,
		userId:     userId,
	}, nil
}

// setTFLogFields adds relevant fields to the context for terraform logging purposes.
func (r *userResource) setTFLogFields(ctx context.Context, arg *clientArg) context.Context {
	ctx = tflog.SetField(ctx, "project_id", arg.projectId)
	ctx = tflog.SetField(ctx, "instance_id", arg.instanceId)
	ctx = tflog.SetField(ctx, "region", arg.region)
	ctx = tflog.SetField(ctx, "user_id", arg.userId)

	return ctx
}

// expandRoles converts a Terraform list of roles to a string slice.
func (r *userResource) expandRoles(ctx context.Context, rolesSet types.List, diags *diag.Diagnostics) []string {
	if rolesSet.IsNull() || rolesSet.IsUnknown() {
		return nil
	}
	var roles []string
	diags.Append(rolesSet.ElementsAs(ctx, &roles, false)...)
	slices.Sort(roles)
	return roles
}