package store

import (
	"database/sql"
	"encoding/json"
	"time"
)

// AppTelemetryRecord holds per-app telemetry received from a controller report.
type AppTelemetryRecord struct {
	AppName         string   `json:"app_name"`
	DisplayName     string   `json:"display_name"`
	Containers      []string `json:"containers"`
	MemoryCurrentMB float64  `json:"memory_current_mb"`
	MemoryAvgMB     float64  `json:"memory_avg_mb"`
	MemoryPeakMB    float64  `json:"memory_peak_mb"`
	CPUAvgPercent   float64  `json:"cpu_avg_percent"`
	CatalogEstimate string   `json:"catalog_estimate"`
	CatalogLimit    string   `json:"catalog_limit"`
	LogErrors       int      `json:"log_errors"`
	LogWarnings     int      `json:"log_warnings"`
	Issues          []struct {
		Severity string    `json:"severity"`
		Message  string    `json:"message"`
		Count    int       `json:"count"`
		LastSeen time.Time `json:"last_seen"`
	} `json:"issues,omitempty"`
}

// FleetAppSummary holds fleet-wide aggregate stats for one app.
type FleetAppSummary struct {
	AppName         string
	DisplayName     string
	DeploymentCount int
	AvgMemoryMB     float64
	PeakMemoryMB    float64
	P95MemoryMB     float64
	AvgCPU          float64
	TotalErrors     int
	TotalWarnings   int
	CatalogEstimate string
	CatalogLimit    string
}

// AppTelemetryPoint holds one time-series data point for chart rendering.
type AppTelemetryPoint struct {
	ReportedAt    time.Time
	CustomerID    string
	MemoryAvgMB   float64
	MemoryPeakMB  float64
	CPUAvgPercent float64
	LogErrors     int
	LogWarnings   int
}

// AppCustomerStats holds per-customer resource stats for an app.
type AppCustomerStats struct {
	CustomerID   string
	AvgMemoryMB  float64
	PeakMemoryMB float64
	AvgCPU       float64
	TotalErrors  int
	LastReport   time.Time
}

// CustomerAppSummary holds per-app stats for a specific customer.
type CustomerAppSummary struct {
	AppName         string
	DisplayName     string
	MemoryCurrentMB float64
	MemoryAvgMB     float64
	MemoryPeakMB    float64
	CatalogLimit    string
	LogErrors       int
	LogWarnings     int
}

// AppIssue holds a known log issue for an app across the fleet.
type AppIssue struct {
	ID                int
	AppName           string
	Fingerprint       string
	Severity          string
	Message           string
	FirstSeen         time.Time
	LastSeen          time.Time
	OccurrenceCount   int
	AffectedCustomers []string
}

// SaveAppTelemetry inserts telemetry records for a customer report into the database.
func (s *Store) SaveAppTelemetry(customerID string, reportedAt time.Time, records []AppTelemetryRecord) error {
	if len(records) == 0 {
		return nil
	}

	tx, err := s.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	stmt, err := tx.Prepare(`
		INSERT INTO app_telemetry
			(customer_id, app_name, display_name, reported_at,
			 memory_current_mb, memory_avg_mb, memory_peak_mb, cpu_avg_percent,
			 catalog_estimate, catalog_limit, log_errors, log_warnings,
			 containers_json, issues_json)
		VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`)
	if err != nil {
		return err
	}
	defer stmt.Close()

	for _, r := range records {
		containersJSON, _ := json.Marshal(r.Containers)
		issuesJSON, _ := json.Marshal(r.Issues)

		if _, err := stmt.Exec(
			customerID, r.AppName, r.DisplayName, reportedAt,
			r.MemoryCurrentMB, r.MemoryAvgMB, r.MemoryPeakMB, r.CPUAvgPercent,
			r.CatalogEstimate, r.CatalogLimit, r.LogErrors, r.LogWarnings,
			string(containersJSON), string(issuesJSON),
		); err != nil {
			return err
		}

		// Upsert log issues
		for _, issue := range r.Issues {
			fp := fingerprintIssue(issue.Message)
			if err := upsertAppIssue(tx, r.AppName, fp, issue.Severity, issue.Message, customerID, issue.LastSeen); err != nil {
				s.logger.Printf("[WARN] upsertAppIssue %s/%s: %v", r.AppName, fp[:min(len(fp), 20)], err)
			}
		}
	}

	return tx.Commit()
}

// upsertAppIssue inserts or updates a known log issue record.
func upsertAppIssue(tx *sql.Tx, appName, fingerprint, severity, message, customerID string, lastSeen time.Time) error {
	// Try insert first
	_, err := tx.Exec(`
		INSERT INTO app_log_issues (app_name, fingerprint, severity, message, first_seen, last_seen, occurrence_count, affected_customers)
		VALUES (?, ?, ?, ?, ?, ?, 1, ?)
		ON CONFLICT(app_name, fingerprint) DO UPDATE SET
			last_seen = CASE WHEN excluded.last_seen > last_seen THEN excluded.last_seen ELSE last_seen END,
			occurrence_count = occurrence_count + 1`,
		appName, fingerprint, severity, message, lastSeen, lastSeen, `[]`)
	if err != nil {
		return err
	}

	// Update affected_customers JSON — read current, add if missing, write back
	var affectedJSON string
	err = tx.QueryRow(`SELECT affected_customers FROM app_log_issues WHERE app_name = ? AND fingerprint = ?`,
		appName, fingerprint).Scan(&affectedJSON)
	if err != nil {
		return nil // non-critical
	}

	var customers []string
	json.Unmarshal([]byte(affectedJSON), &customers)
	found := false
	for _, c := range customers {
		if c == customerID {
			found = true
			break
		}
	}
	if !found {
		customers = append(customers, customerID)
		newJSON, _ := json.Marshal(customers)
		tx.Exec(`UPDATE app_log_issues SET affected_customers = ? WHERE app_name = ? AND fingerprint = ?`,
			string(newJSON), appName, fingerprint)
	}

	return nil
}

// fingerprintIssue creates a short fingerprint key from a message string.
func fingerprintIssue(msg string) string {
	if len(msg) > 100 {
		msg = msg[:100]
	}
	return msg
}

// min returns the smaller of two ints.
func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

// GetFleetAppSummary returns fleet-wide aggregate stats for all apps since the given time.
func (s *Store) GetFleetAppSummary(since time.Time) ([]FleetAppSummary, error) {
	rows, err := s.db.Query(`
		SELECT app_name,
		       MAX(display_name) as display_name,
		       COUNT(DISTINCT customer_id) as deployment_count,
		       AVG(memory_avg_mb) as avg_memory_mb,
		       MAX(memory_peak_mb) as peak_memory_mb,
		       AVG(cpu_avg_percent) as avg_cpu,
		       SUM(log_errors) as total_errors,
		       SUM(log_warnings) as total_warnings,
		       MAX(catalog_estimate) as catalog_estimate,
		       MAX(catalog_limit) as catalog_limit
		FROM app_telemetry
		WHERE reported_at > ?
		GROUP BY app_name
		ORDER BY deployment_count DESC, avg_memory_mb DESC`, since)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var summaries []FleetAppSummary
	for rows.Next() {
		var fs FleetAppSummary
		if err := rows.Scan(
			&fs.AppName, &fs.DisplayName, &fs.DeploymentCount,
			&fs.AvgMemoryMB, &fs.PeakMemoryMB, &fs.AvgCPU,
			&fs.TotalErrors, &fs.TotalWarnings,
			&fs.CatalogEstimate, &fs.CatalogLimit,
		); err != nil {
			continue
		}
		summaries = append(summaries, fs)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}

	// Calculate P95 memory per app
	for i := range summaries {
		p95, err := s.calcP95Memory(summaries[i].AppName, since)
		if err == nil {
			summaries[i].P95MemoryMB = p95
		}
	}

	return summaries, nil
}

// calcP95Memory returns the approximate P95 memory_peak_mb for an app since the given time.
func (s *Store) calcP95Memory(appName string, since time.Time) (float64, error) {
	// Get count first
	var count int
	err := s.db.QueryRow(`SELECT COUNT(*) FROM app_telemetry WHERE app_name = ? AND reported_at > ?`,
		appName, since).Scan(&count)
	if err != nil || count == 0 {
		return 0, err
	}

	offset := int(float64(count) * 0.95)
	if offset >= count {
		offset = count - 1
	}

	var p95 float64
	err = s.db.QueryRow(`
		SELECT memory_peak_mb FROM app_telemetry
		WHERE app_name = ? AND reported_at > ?
		ORDER BY memory_peak_mb ASC
		LIMIT 1 OFFSET ?`, appName, since, offset).Scan(&p95)
	if err != nil {
		return 0, err
	}
	return p95, nil
}

// GetAppTelemetryHistory returns time-series telemetry for a specific app.
func (s *Store) GetAppTelemetryHistory(appName string, since time.Time) ([]AppTelemetryPoint, error) {
	rows, err := s.db.Query(`
		SELECT reported_at, customer_id, memory_avg_mb, memory_peak_mb, cpu_avg_percent, log_errors, log_warnings
		FROM app_telemetry
		WHERE app_name = ? AND reported_at > ?
		ORDER BY reported_at ASC`, appName, since)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var points []AppTelemetryPoint
	for rows.Next() {
		var p AppTelemetryPoint
		if err := rows.Scan(&p.ReportedAt, &p.CustomerID, &p.MemoryAvgMB, &p.MemoryPeakMB,
			&p.CPUAvgPercent, &p.LogErrors, &p.LogWarnings); err != nil {
			continue
		}
		points = append(points, p)
	}
	return points, rows.Err()
}

// GetAppCustomerBreakdown returns per-customer resource stats for an app.
func (s *Store) GetAppCustomerBreakdown(appName string, since time.Time) ([]AppCustomerStats, error) {
	rows, err := s.db.Query(`
		SELECT customer_id, AVG(memory_avg_mb), MAX(memory_peak_mb), AVG(cpu_avg_percent),
		       SUM(log_errors), MAX(reported_at)
		FROM app_telemetry
		WHERE app_name = ? AND reported_at > ?
		GROUP BY customer_id
		ORDER BY AVG(memory_avg_mb) DESC`, appName, since)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var stats []AppCustomerStats
	for rows.Next() {
		var cs AppCustomerStats
		if err := rows.Scan(&cs.CustomerID, &cs.AvgMemoryMB, &cs.PeakMemoryMB, &cs.AvgCPU,
			&cs.TotalErrors, &cs.LastReport); err != nil {
			continue
		}
		stats = append(stats, cs)
	}
	return stats, rows.Err()
}

// GetCustomerAppSummary returns per-app telemetry summary for a specific customer.
func (s *Store) GetCustomerAppSummary(customerID string, since time.Time) ([]CustomerAppSummary, error) {
	// 7-day averages/peaks
	rows, err := s.db.Query(`
		SELECT app_name, MAX(display_name), AVG(memory_avg_mb), MAX(memory_peak_mb),
		       MAX(catalog_limit), SUM(log_errors), SUM(log_warnings)
		FROM app_telemetry
		WHERE customer_id = ? AND reported_at > ?
		GROUP BY app_name
		ORDER BY AVG(memory_avg_mb) DESC`, customerID, since)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	summaryMap := make(map[string]*CustomerAppSummary)
	var order []string
	for rows.Next() {
		var cs CustomerAppSummary
		if err := rows.Scan(&cs.AppName, &cs.DisplayName, &cs.MemoryAvgMB, &cs.MemoryPeakMB,
			&cs.CatalogLimit, &cs.LogErrors, &cs.LogWarnings); err != nil {
			continue
		}
		summaryMap[cs.AppName] = &cs
		order = append(order, cs.AppName)
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}

	// Get current memory from most recent report per app
	currentRows, err := s.db.Query(`
		SELECT app_name, memory_current_mb
		FROM app_telemetry
		WHERE customer_id = ? AND reported_at = (
			SELECT MAX(reported_at) FROM app_telemetry at2
			WHERE at2.customer_id = ? AND at2.app_name = app_telemetry.app_name
		)`, customerID, customerID)
	if err == nil {
		defer currentRows.Close()
		for currentRows.Next() {
			var appName string
			var currentMB float64
			if err := currentRows.Scan(&appName, &currentMB); err == nil {
				if s, ok := summaryMap[appName]; ok {
					s.MemoryCurrentMB = currentMB
				}
			}
		}
	}

	result := make([]CustomerAppSummary, 0, len(order))
	for _, name := range order {
		if s, ok := summaryMap[name]; ok {
			result = append(result, *s)
		}
	}
	return result, nil
}

// GetAppIssues returns recent known issues for a specific app.
func (s *Store) GetAppIssues(appName string, limit int) ([]AppIssue, error) {
	rows, err := s.db.Query(`
		SELECT id, app_name, fingerprint, severity, message, first_seen, last_seen,
		       occurrence_count, affected_customers
		FROM app_log_issues
		WHERE app_name = ?
		ORDER BY last_seen DESC
		LIMIT ?`, appName, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	return scanAppIssues(rows)
}

// GetRecentIssuesAllApps returns the most recently seen issues across all apps.
func (s *Store) GetRecentIssuesAllApps(limit int) ([]AppIssue, error) {
	rows, err := s.db.Query(`
		SELECT id, app_name, fingerprint, severity, message, first_seen, last_seen,
		       occurrence_count, affected_customers
		FROM app_log_issues
		ORDER BY last_seen DESC
		LIMIT ?`, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	return scanAppIssues(rows)
}

func scanAppIssues(rows *sql.Rows) ([]AppIssue, error) {
	var issues []AppIssue
	for rows.Next() {
		var ai AppIssue
		var affectedJSON string
		if err := rows.Scan(&ai.ID, &ai.AppName, &ai.Fingerprint, &ai.Severity, &ai.Message,
			&ai.FirstSeen, &ai.LastSeen, &ai.OccurrenceCount, &affectedJSON); err != nil {
			continue
		}
		json.Unmarshal([]byte(affectedJSON), &ai.AffectedCustomers)
		issues = append(issues, ai)
	}
	return issues, rows.Err()
}

// PruneAppTelemetry removes telemetry rows older than the given time.
func (s *Store) PruneAppTelemetry(before time.Time) (int64, error) {
	res, err := s.db.Exec("DELETE FROM app_telemetry WHERE reported_at < ?", before)
	if err != nil {
		return 0, err
	}
	return res.RowsAffected()
}

// PruneStaleIssues removes issue records not seen since the given time.
func (s *Store) PruneStaleIssues(notSeenSince time.Time) (int64, error) {
	res, err := s.db.Exec("DELETE FROM app_log_issues WHERE last_seen < ?", notSeenSince)
	if err != nil {
		return 0, err
	}
	return res.RowsAffected()
}

// DeleteAppTelemetry removes all telemetry records for a specific app.
func (s *Store) DeleteAppTelemetry(appName string) (int64, error) {
	res, err := s.db.Exec("DELETE FROM app_telemetry WHERE app_name = ?", appName)
	if err != nil {
		return 0, err
	}
	return res.RowsAffected()
}

// DeleteAppIssues removes all known-issue records for a specific app.
func (s *Store) DeleteAppIssues(appName string) (int64, error) {
	res, err := s.db.Exec("DELETE FROM app_log_issues WHERE app_name = ?", appName)
	if err != nil {
		return 0, err
	}
	return res.RowsAffected()
}