// Copyright (c) EZSCALE.
// SPDX-License-Identifier: MPL-2.0

package provider

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"

	"terraform-provider-virtfusion/internal/client"

	"github.com/hashicorp/terraform-plugin-framework/attr"
	"github.com/hashicorp/terraform-plugin-framework/diag"
	"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/stringdefault"
	"github.com/hashicorp/terraform-plugin-framework/resource/schema/stringplanmodifier"
	"github.com/hashicorp/terraform-plugin-framework/types"
)

var (
	_ resource.Resource              = &ServerFirewallResource{}
	_ resource.ResourceWithConfigure = &ServerFirewallResource{}
)

// NewServerFirewallResource returns a new resource for managing server firewalls.
func NewServerFirewallResource() resource.Resource {
	return &ServerFirewallResource{}
}

// ServerFirewallResource defines the resource implementation.
type ServerFirewallResource struct {
	client *client.Client
}

// ServerFirewallResourceModel describes the resource data model.
type ServerFirewallResourceModel struct {
	ID            types.String `tfsdk:"id"`
	ServerID      types.Int64  `tfsdk:"server_id"`
	InterfaceName types.String `tfsdk:"interface_name"`
	Rules         types.List   `tfsdk:"rules"`
}

// FirewallRuleModel describes a single firewall rule.
type FirewallRuleModel struct {
	Action    types.String `tfsdk:"action"`
	Direction types.String `tfsdk:"direction"`
	Protocol  types.String `tfsdk:"protocol"`
	Port      types.String `tfsdk:"port"`
	IP        types.String `tfsdk:"ip"`
}

func (r *ServerFirewallResource) Metadata(_ context.Context, req resource.MetadataRequest, resp *resource.MetadataResponse) {
	resp.TypeName = req.ProviderTypeName + "_server_firewall"
}

func (r *ServerFirewallResource) Schema(_ context.Context, _ resource.SchemaRequest, resp *resource.SchemaResponse) {
	resp.Schema = schema.Schema{
		MarkdownDescription: "Manages a VirtFusion server firewall.",
		Attributes: map[string]schema.Attribute{
			"id": schema.StringAttribute{
				MarkdownDescription: "Composite identifier in the format `server_id/interface_name`.",
				Computed:            true,
				PlanModifiers: []planmodifier.String{
					stringplanmodifier.UseStateForUnknown(),
				},
			},
			"server_id": schema.Int64Attribute{
				MarkdownDescription: "The ID of the server.",
				Required:            true,
			},
			"interface_name": schema.StringAttribute{
				MarkdownDescription: "The network interface name. Defaults to `eth0`.",
				Optional:            true,
				Computed:            true,
				Default:             stringdefault.StaticString("eth0"),
			},
			"rules": schema.ListNestedAttribute{
				MarkdownDescription: "The firewall rules.",
				Optional:            true,
				NestedObject: schema.NestedAttributeObject{
					Attributes: map[string]schema.Attribute{
						"action": schema.StringAttribute{
							MarkdownDescription: "The action for the rule (e.g. `accept`, `drop`).",
							Required:            true,
						},
						"direction": schema.StringAttribute{
							MarkdownDescription: "The direction for the rule (e.g. `in`, `out`).",
							Required:            true,
						},
						"protocol": schema.StringAttribute{
							MarkdownDescription: "The protocol for the rule (e.g. `tcp`, `udp`).",
							Required:            true,
						},
						"port": schema.StringAttribute{
							MarkdownDescription: "The port or port range for the rule.",
							Required:            true,
						},
						"ip": schema.StringAttribute{
							MarkdownDescription: "The IP address or CIDR for the rule.",
							Required:            true,
						},
					},
				},
			},
		},
	}
}

func (r *ServerFirewallResource) Configure(_ context.Context, req resource.ConfigureRequest, resp *resource.ConfigureResponse) {
	if req.ProviderData == nil {
		return
	}

	c, ok := req.ProviderData.(*client.Client)
	if !ok {
		resp.Diagnostics.AddError(
			"Unexpected Resource Configure Type",
			fmt.Sprintf("Expected *client.Client, got: %T.", req.ProviderData),
		)
		return
	}

	r.client = c
}

func (r *ServerFirewallResource) Create(ctx context.Context, req resource.CreateRequest, resp *resource.CreateResponse) {
	var data ServerFirewallResourceModel
	resp.Diagnostics.Append(req.Plan.Get(ctx, &data)...)
	if resp.Diagnostics.HasError() {
		return
	}

	serverID := data.ServerID.ValueInt64()
	iface := data.InterfaceName.ValueString()

	// Enable the firewall
	_, err := r.client.Post(ctx, fmt.Sprintf("/servers/%d/firewall/%s/enable", serverID, iface), nil)
	if err != nil {
		resp.Diagnostics.AddError("Error enabling server firewall", err.Error())
		return
	}

	// Set rules if provided
	rules, diags := r.extractRules(ctx, data)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}

	if len(rules) > 0 {
		rulesReq := client.FirewallSetRulesRequest{Rules: rules}
		_, err = r.client.Post(ctx, fmt.Sprintf("/servers/%d/firewall/%s/rules", serverID, iface), rulesReq)
		if err != nil {
			resp.Diagnostics.AddError("Error setting firewall rules", err.Error())
			return
		}
	}

	data.ID = types.StringValue(fmt.Sprintf("%d/%s", serverID, iface))

	resp.Diagnostics.Append(resp.State.Set(ctx, &data)...)
}

func (r *ServerFirewallResource) Read(ctx context.Context, req resource.ReadRequest, resp *resource.ReadResponse) {
	var data ServerFirewallResourceModel
	resp.Diagnostics.Append(req.State.Get(ctx, &data)...)
	if resp.Diagnostics.HasError() {
		return
	}

	serverID := data.ServerID.ValueInt64()
	iface := data.InterfaceName.ValueString()

	result, err := r.client.Get(ctx, fmt.Sprintf("/servers/%d/firewall/%s", serverID, iface))
	if err != nil {
		var apiErr *client.APIError
		if errors.As(err, &apiErr) && apiErr.IsNotFound() {
			resp.State.RemoveResource(ctx)
			return
		}
		resp.Diagnostics.AddError("Error reading server firewall", err.Error())
		return
	}

	var fwResp client.FirewallResponse
	if err := json.Unmarshal(result, &fwResp); err != nil {
		resp.Diagnostics.AddError("Error parsing firewall response", err.Error())
		return
	}

	// If the firewall is not enabled, remove from state
	if !fwResp.Data.Enabled {
		resp.State.RemoveResource(ctx)
		return
	}

	data.ID = types.StringValue(fmt.Sprintf("%d/%s", serverID, iface))

	// Map API rules to the model
	ruleObjects := make([]attr.Value, len(fwResp.Data.Rules))
	for i, rule := range fwResp.Data.Rules {
		ruleObj, diags := types.ObjectValue(
			firewallRuleAttrTypes(),
			map[string]attr.Value{
				"action":    types.StringValue(rule.Action),
				"direction": types.StringValue(rule.Direction),
				"protocol":  types.StringValue(rule.Protocol),
				"port":      types.StringValue(rule.Port),
				"ip":        types.StringValue(rule.IP),
			},
		)
		resp.Diagnostics.Append(diags...)
		if resp.Diagnostics.HasError() {
			return
		}
		ruleObjects[i] = ruleObj
	}

	rulesList, diags := types.ListValue(types.ObjectType{AttrTypes: firewallRuleAttrTypes()}, ruleObjects)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}
	data.Rules = rulesList

	resp.Diagnostics.Append(resp.State.Set(ctx, &data)...)
}

func (r *ServerFirewallResource) Update(ctx context.Context, req resource.UpdateRequest, resp *resource.UpdateResponse) {
	var data ServerFirewallResourceModel
	resp.Diagnostics.Append(req.Plan.Get(ctx, &data)...)
	if resp.Diagnostics.HasError() {
		return
	}

	serverID := data.ServerID.ValueInt64()
	iface := data.InterfaceName.ValueString()

	rules, diags := r.extractRules(ctx, data)
	resp.Diagnostics.Append(diags...)
	if resp.Diagnostics.HasError() {
		return
	}

	rulesReq := client.FirewallSetRulesRequest{Rules: rules}
	_, err := r.client.Post(ctx, fmt.Sprintf("/servers/%d/firewall/%s/rules", serverID, iface), rulesReq)
	if err != nil {
		resp.Diagnostics.AddError("Error updating firewall rules", err.Error())
		return
	}

	data.ID = types.StringValue(fmt.Sprintf("%d/%s", serverID, iface))

	resp.Diagnostics.Append(resp.State.Set(ctx, &data)...)
}

func (r *ServerFirewallResource) Delete(ctx context.Context, req resource.DeleteRequest, resp *resource.DeleteResponse) {
	var data ServerFirewallResourceModel
	resp.Diagnostics.Append(req.State.Get(ctx, &data)...)
	if resp.Diagnostics.HasError() {
		return
	}

	serverID := data.ServerID.ValueInt64()
	iface := data.InterfaceName.ValueString()

	_, err := r.client.Post(ctx, fmt.Sprintf("/servers/%d/firewall/%s/disable", serverID, iface), nil)
	if err != nil {
		var apiErr *client.APIError
		if errors.As(err, &apiErr) && apiErr.IsNotFound() {
			return
		}
		resp.Diagnostics.AddError("Error disabling server firewall", err.Error())
	}
}

// extractRules converts the rules list from the model into client.FirewallRule slice.
func (r *ServerFirewallResource) extractRules(ctx context.Context, data ServerFirewallResourceModel) ([]client.FirewallRule, diag.Diagnostics) {
	var diags diag.Diagnostics

	if data.Rules.IsNull() || data.Rules.IsUnknown() {
		return nil, diags
	}

	var ruleModels []FirewallRuleModel
	diags.Append(data.Rules.ElementsAs(ctx, &ruleModels, false)...)
	if diags.HasError() {
		return nil, diags
	}

	rules := make([]client.FirewallRule, len(ruleModels))
	for i, rm := range ruleModels {
		rules[i] = client.FirewallRule{
			Action:    rm.Action.ValueString(),
			Direction: rm.Direction.ValueString(),
			Protocol:  rm.Protocol.ValueString(),
			Port:      rm.Port.ValueString(),
			IP:        rm.IP.ValueString(),
		}
	}
	return rules, diags
}

// firewallRuleAttrTypes returns the attribute types for a firewall rule object.
func firewallRuleAttrTypes() map[string]attr.Type {
	return map[string]attr.Type{
		"action":    types.StringType,
		"direction": types.StringType,
		"protocol":  types.StringType,
		"port":      types.StringType,
		"ip":        types.StringType,
	}
}