package services

import (
	"context"
	"fmt"
	"time"

	"github.com/yourusername/victorialogs-manager/internal/models"
	"github.com/yourusername/victorialogs-manager/pkg/vlogs"
)

// LogsService handles log querying business logic
type LogsService struct {
	vlogsClient *vlogs.Client
}

// NewLogsService creates a new logs service
func NewLogsService(vlogsClient *vlogs.Client) *LogsService {
	return &LogsService{
		vlogsClient: vlogsClient,
	}
}

// QueryLogsRequest represents a log query request
type QueryLogsRequest struct {
	Query     string    `json:"query" binding:"required"`
	StartTime time.Time `json:"start_time,omitempty"`
	EndTime   time.Time `json:"end_time,omitempty"`
	Limit     int       `json:"limit,omitempty"`
	Offset    int       `json:"offset,omitempty"`
}

// QueryLogsResponse represents a log query response
type QueryLogsResponse struct {
	Logs       []vlogs.LogEntry `json:"logs"`
	TotalCount int              `json:"total_count"`
	Took       int              `json:"took_ms"`
	Query      string           `json:"query"`
}

// QueryLogs executes a LogsQL query with authentication and rate limiting
func (s *LogsService) QueryLogs(ctx context.Context, req *QueryLogsRequest, userRole models.Role) (*QueryLogsResponse, error) {
	// Validate query
	if err := s.validateQuery(req.Query); err != nil {
		return nil, fmt.Errorf("invalid query: %w", err)
	}

	// Apply default limits based on role
	if req.Limit == 0 {
		req.Limit = s.getDefaultLimit(userRole)
	}

	// Enforce maximum limits
	maxLimit := s.getMaxLimit(userRole)
	if req.Limit > maxLimit {
		req.Limit = maxLimit
	}

	// Set default time range if not specified (last 15 minutes)
	if req.StartTime.IsZero() {
		req.StartTime = time.Now().Add(-15 * time.Minute)
	}
	if req.EndTime.IsZero() {
		req.EndTime = time.Now()
	}

	// Execute query
	params := vlogs.QueryParams{
		Query:  req.Query,
		Start:  req.StartTime,
		End:    req.EndTime,
		Limit:  req.Limit,
		Offset: req.Offset,
	}

	result, err := s.vlogsClient.Query(ctx, params)
	if err != nil {
		return nil, fmt.Errorf("query failed: %w", err)
	}

	return &QueryLogsResponse{
		Logs:       result.Logs,
		TotalCount: result.TotalCount,
		Took:       result.Took,
		Query:      req.Query,
	}, nil
}

// StatsQueryRequest represents a stats query request
type StatsQueryRequest struct {
	Query     string    `json:"query" binding:"required"`
	StartTime time.Time `json:"start_time" binding:"required"`
	EndTime   time.Time `json:"end_time" binding:"required"`
	Step      string    `json:"step,omitempty"` // e.g., "5m", "1h"
}

// StatsQueryResponse represents a stats query response
type StatsQueryResponse struct {
	Data []vlogs.StatsDataPoint `json:"data"`
}

// StatsQuery executes a stats query
func (s *LogsService) StatsQuery(ctx context.Context, req *StatsQueryRequest) (*StatsQueryResponse, error) {
	// Validate query
	if err := s.validateQuery(req.Query); err != nil {
		return nil, fmt.Errorf("invalid query: %w", err)
	}

	// Set default step if not specified
	if req.Step == "" {
		// Calculate appropriate step based on time range
		duration := req.EndTime.Sub(req.StartTime)
		req.Step = s.calculateStep(duration)
	}

	params := vlogs.StatsParams{
		Query: req.Query,
		Start: req.StartTime,
		End:   req.EndTime,
		Step:  req.Step,
	}

	result, err := s.vlogsClient.StatsQuery(ctx, params)
	if err != nil {
		return nil, fmt.Errorf("stats query failed: %w", err)
	}

	return &StatsQueryResponse{
		Data: result.Data,
	}, nil
}

// GetFacetsRequest represents a facets request
type GetFacetsRequest struct {
	Query     string    `json:"query"`
	StartTime time.Time `json:"start_time"`
	EndTime   time.Time `json:"end_time"`
	Field     string    `json:"field,omitempty"`
}

// GetFacetsResponse represents a facets response
type GetFacetsResponse struct {
	Facets []vlogs.Facet `json:"facets"`
}

// GetFacets gets facet values for a field
func (s *LogsService) GetFacets(ctx context.Context, req *GetFacetsRequest) (*GetFacetsResponse, error) {
	// Set default time range if not specified
	if req.StartTime.IsZero() {
		req.StartTime = time.Now().Add(-15 * time.Minute)
	}
	if req.EndTime.IsZero() {
		req.EndTime = time.Now()
	}

	params := vlogs.FacetsParams{
		Query: req.Query,
		Start: req.StartTime,
		End:   req.EndTime,
		Field: req.Field,
	}

	result, err := s.vlogsClient.GetFacets(ctx, params)
	if err != nil {
		return nil, fmt.Errorf("facets query failed: %w", err)
	}

	return &GetFacetsResponse{
		Facets: result.Facets,
	}, nil
}

// TailLogsRequest represents a tail request
type TailLogsRequest struct {
	Query string `json:"query" binding:"required"`
	Limit int    `json:"limit,omitempty"`
}

// TailLogs starts tailing logs in real-time
func (s *LogsService) TailLogs(ctx context.Context, req *TailLogsRequest) (<-chan vlogs.LogEntry, <-chan error, error) {
	// Validate query
	if err := s.validateQuery(req.Query); err != nil {
		return nil, nil, fmt.Errorf("invalid query: %w", err)
	}

	// Set default limit
	if req.Limit == 0 {
		req.Limit = 100
	}

	params := vlogs.TailParams{
		Query: req.Query,
		Limit: req.Limit,
	}

	return s.vlogsClient.Tail(ctx, params)
}

// ExportLogsRequest represents an export request
type ExportLogsRequest struct {
	Query     string    `json:"query" binding:"required"`
	StartTime time.Time `json:"start_time" binding:"required"`
	EndTime   time.Time `json:"end_time" binding:"required"`
	Format    string    `json:"format"` // "json" or "csv"
}

// ExportLogs exports logs in the specified format
func (s *LogsService) ExportLogs(ctx context.Context, req *ExportLogsRequest, userRole models.Role) ([]vlogs.LogEntry, error) {
	// Validate query
	if err := s.validateQuery(req.Query); err != nil {
		return nil, fmt.Errorf("invalid query: %w", err)
	}

	// Enforce export limits
	maxExportLimit := s.getMaxExportLimit(userRole)

	params := vlogs.QueryParams{
		Query:  req.Query,
		Start:  req.StartTime,
		End:    req.EndTime,
		Limit:  maxExportLimit,
		Offset: 0,
	}

	result, err := s.vlogsClient.Query(ctx, params)
	if err != nil {
		return nil, fmt.Errorf("export query failed: %w", err)
	}

	return result.Logs, nil
}

// validateQuery validates a LogsQL query
func (s *LogsService) validateQuery(query string) error {
	if query == "" {
		return fmt.Errorf("query cannot be empty")
	}

	// Check query length
	if len(query) > 10000 {
		return fmt.Errorf("query too long (max 10000 characters)")
	}

	// Add more validation as needed
	// For example, check for dangerous patterns

	return nil
}

// getDefaultLimit returns the default query limit for a role
func (s *LogsService) getDefaultLimit(role models.Role) int {
	switch role {
	case models.RoleAdmin:
		return 1000
	case models.RoleEditor:
		return 500
	case models.RoleAnalyst:
		return 500
	case models.RoleViewer:
		return 100
	default:
		return 100
	}
}

// getMaxLimit returns the maximum query limit for a role
func (s *LogsService) getMaxLimit(role models.Role) int {
	switch role {
	case models.RoleAdmin:
		return 10000
	case models.RoleEditor:
		return 5000
	case models.RoleAnalyst:
		return 5000
	case models.RoleViewer:
		return 1000
	default:
		return 1000
	}
}

// getMaxExportLimit returns the maximum export limit for a role
func (s *LogsService) getMaxExportLimit(role models.Role) int {
	switch role {
	case models.RoleAdmin:
		return 100000
	case models.RoleEditor:
		return 50000
	case models.RoleAnalyst:
		return 50000
	case models.RoleViewer:
		return 10000
	default:
		return 10000
	}
}

// calculateStep calculates an appropriate step for stats queries based on duration
func (s *LogsService) calculateStep(duration time.Duration) string {
	switch {
	case duration <= time.Hour:
		return "1m"
	case duration <= 6*time.Hour:
		return "5m"
	case duration <= 24*time.Hour:
		return "15m"
	case duration <= 7*24*time.Hour:
		return "1h"
	default:
		return "6h"
	}
}