package tasks

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"log/slog"
	"time"

	"forgejo.digital-droplets.de/philschlo/proxui/platform/jobs"
	"github.com/hibiken/asynq"
)

const TypeProxmoxTaskPoll = jobs.TypeProxmoxTaskPoll

var ErrClusterNotFound = errors.New("cluster not found")

type ProxmoxTaskPollPayload = jobs.ProxmoxTaskPollPayload

type ProxmoxTaskStatus struct {
	Status     string
	ExitStatus string
}

type ProxmoxTaskClient interface {
	GetTaskStatus(ctx context.Context, node string, upid string) (ProxmoxTaskStatus, error)
}

type ProxmoxTaskClientResolver interface {
	ResolveTaskClient(ctx context.Context, clusterID string) (ProxmoxTaskClient, error)
}

type VMStatusStore interface {
	SetVMStatus(ctx context.Context, vmID string, status string) error
}

type AuditWriter interface {
	WriteAudit(ctx context.Context, event AuditEvent) error
}

type AuditEvent struct {
	TenantID   string
	ProfileID  string
	Action     string
	TargetType string
	TargetID   string
	Metadata   map[string]any
}

type ProxmoxTaskPollHandler struct {
	resolver    ProxmoxTaskClientResolver
	vmStore     VMStatusStore
	auditWriter AuditWriter
	logger      *slog.Logger
	maxPolls    int
	pollDelay   time.Duration
}

func NewProxmoxTaskPollHandler(
	resolver ProxmoxTaskClientResolver,
	vmStore VMStatusStore,
	auditWriter AuditWriter,
	logger *slog.Logger,
) ProxmoxTaskPollHandler {
	return ProxmoxTaskPollHandler{
		resolver:    resolver,
		vmStore:     vmStore,
		auditWriter: auditWriter,
		logger:      logger,
		maxPolls:    60,
		pollDelay:   2 * time.Second,
	}
}

func (h ProxmoxTaskPollHandler) WithPolling(maxPolls int, pollDelay time.Duration) ProxmoxTaskPollHandler {
	h.maxPolls = maxPolls
	h.pollDelay = pollDelay
	return h
}

func NewProxmoxTaskPollTask(payload ProxmoxTaskPollPayload) (*asynq.Task, error) {
	body, err := json.Marshal(payload)
	if err != nil {
		return nil, err
	}
	return asynq.NewTask(TypeProxmoxTaskPoll, body), nil
}

func (h ProxmoxTaskPollHandler) ProcessTask(ctx context.Context, task *asynq.Task) error {
	payload, err := decodeProxmoxTaskPollPayload(task.Payload())
	if err != nil {
		return err
	}

	client, err := h.resolver.ResolveTaskClient(ctx, payload.ClusterID)
	if err != nil {
		return fmt.Errorf("resolve proxmox task client: %w", err)
	}

	for attempt := 0; attempt < h.maxPolls; attempt++ {
		status, err := client.GetTaskStatus(ctx, payload.Node, payload.UPID)
		if err != nil {
			return fmt.Errorf("poll proxmox task status: %w", err)
		}

		if isTaskRunning(status) {
			if err := sleepContext(ctx, h.pollDelay); err != nil {
				return err
			}
			continue
		}

		if isTaskSuccessful(status) {
			return h.completeTarget(ctx, payload, payload.SuccessStatus, status)
		}

		return h.completeTarget(ctx, payload, "failed", status)
	}

	return fmt.Errorf("proxmox task %s still running after %d polls", payload.UPID, h.maxPolls)
}

func (h ProxmoxTaskPollHandler) completeTarget(ctx context.Context, payload ProxmoxTaskPollPayload, finalStatus string, taskStatus ProxmoxTaskStatus) error {
	if payload.TargetType != "vm" {
		return fmt.Errorf("unsupported target type %q", payload.TargetType)
	}

	if err := h.vmStore.SetVMStatus(ctx, payload.TargetID, finalStatus); err != nil {
		return fmt.Errorf("set vm status: %w", err)
	}

	if err := h.auditWriter.WriteAudit(ctx, AuditEvent{
		TenantID:   payload.TenantID,
		ProfileID:  payload.ProfileID,
		Action:     payload.Action,
		TargetType: payload.TargetType,
		TargetID:   payload.TargetID,
		Metadata: map[string]any{
			"cluster_id":     payload.ClusterID,
			"node":           payload.Node,
			"upid":           payload.UPID,
			"task_status":    taskStatus.Status,
			"exit_status":    taskStatus.ExitStatus,
			"target_status":  finalStatus,
			"success_status": payload.SuccessStatus,
		},
	}); err != nil {
		return fmt.Errorf("write audit event: %w", err)
	}

	h.logger.Info("completed proxmox task poll", "target_type", payload.TargetType, "target_id", payload.TargetID, "status", finalStatus)
	return nil
}

func decodeProxmoxTaskPollPayload(body []byte) (ProxmoxTaskPollPayload, error) {
	var payload ProxmoxTaskPollPayload
	if err := json.Unmarshal(body, &payload); err != nil {
		return ProxmoxTaskPollPayload{}, fmt.Errorf("decode proxmox task poll payload: %w", err)
	}
	if payload.ClusterID == "" {
		return ProxmoxTaskPollPayload{}, fmt.Errorf("cluster_id is required")
	}
	if payload.Node == "" {
		return ProxmoxTaskPollPayload{}, fmt.Errorf("node is required")
	}
	if payload.UPID == "" {
		return ProxmoxTaskPollPayload{}, fmt.Errorf("upid is required")
	}
	if payload.TargetType == "" {
		return ProxmoxTaskPollPayload{}, fmt.Errorf("target_type is required")
	}
	if payload.TargetID == "" {
		return ProxmoxTaskPollPayload{}, fmt.Errorf("target_id is required")
	}
	if payload.TenantID == "" {
		return ProxmoxTaskPollPayload{}, fmt.Errorf("tenant_id is required")
	}
	if payload.Action == "" {
		return ProxmoxTaskPollPayload{}, fmt.Errorf("action is required")
	}
	if payload.SuccessStatus == "" {
		return ProxmoxTaskPollPayload{}, fmt.Errorf("success_status is required")
	}
	return payload, nil
}

func isTaskRunning(status ProxmoxTaskStatus) bool {
	return status.Status == "" || status.Status == "running"
}

func isTaskSuccessful(status ProxmoxTaskStatus) bool {
	return status.Status == "stopped" && status.ExitStatus == "OK"
}

func sleepContext(ctx context.Context, delay time.Duration) error {
	if delay <= 0 {
		return nil
	}

	timer := time.NewTimer(delay)
	defer timer.Stop()

	select {
	case <-ctx.Done():
		return ctx.Err()
	case <-timer.C:
		return nil
	}
}

type SQLVMStatusStore struct {
	db *sql.DB
}

func NewSQLVMStatusStore(db *sql.DB) SQLVMStatusStore {
	return SQLVMStatusStore{db: db}
}

func (s SQLVMStatusStore) SetVMStatus(ctx context.Context, vmID string, status string) error {
	result, err := s.db.ExecContext(ctx, `
		update public.vms
		set status = $2,
			updated_at = now()
		where id = $1
	`, vmID, status)
	if err != nil {
		return err
	}

	rows, err := result.RowsAffected()
	if err != nil {
		return err
	}
	if rows == 0 {
		return fmt.Errorf("vm not found")
	}
	return nil
}

type SQLAuditWriter struct {
	db *sql.DB
}

func NewSQLAuditWriter(db *sql.DB) SQLAuditWriter {
	return SQLAuditWriter{db: db}
}

func (w SQLAuditWriter) WriteAudit(ctx context.Context, event AuditEvent) error {
	metadata, err := json.Marshal(event.Metadata)
	if err != nil {
		return err
	}

	var profileID any
	if event.ProfileID != "" {
		profileID = event.ProfileID
	}

	_, err = w.db.ExecContext(ctx, `
		insert into public.audit_log (
			tenant_id,
			profile_id,
			action,
			target_type,
			target_id,
			metadata
		)
		values ($1, $2, $3, $4, $5, $6::jsonb)
	`, event.TenantID, profileID, event.Action, event.TargetType, event.TargetID, string(metadata))
	return err
}

type UnconfiguredProxmoxTaskClientResolver struct{}

func (UnconfiguredProxmoxTaskClientResolver) ResolveTaskClient(context.Context, string) (ProxmoxTaskClient, error) {
	return nil, fmt.Errorf("proxmox task client resolver is not configured")
}