#Requires -Version 5.1

<#
.SYNOPSIS
    Automated weekly performance monitoring for Jellyfin PostgreSQL database

.DESCRIPTION
    This script:
    1. Runs comprehensive diagnostics
    2. Analyzes slow queries
    3. Tracks index usage over time
    4. Generates weekly performance reports
    5. Optionally runs VACUUM ANALYZE on tables with high dead tuples
    6. Can be scheduled via Task Scheduler

.PARAMETER OutputDirectory
    Directory to save reports (default: reports/weekly)

.PARAMETER EmailReport
    If specified, emails the report (requires email configuration)

.PARAMETER CompareWithPrevious
    Compare current stats with previous week

.EXAMPLE
    .\Weekly-Performance-Monitor.ps1
    
.EXAMPLE
    .\Weekly-Performance-Monitor.ps1 -OutputDirectory "C:\Reports\Jellyfin" -CompareWithPrevious

.EXAMPLE
    .\Weekly-Performance-Monitor.ps1 -AutoVacuumAnalyze -DeadTupleThreshold 10000 -DeadTuplePercentThreshold 20

.EXAMPLE
    # Schedule weekly via Task Scheduler
    $action = New-ScheduledTaskAction -Execute "PowerShell.exe" -Argument "-File C:\Path\To\Weekly-Performance-Monitor.ps1"
    $trigger = New-ScheduledTaskTrigger -Weekly -DaysOfWeek Monday -At 6am
    Register-ScheduledTask -TaskName "Jellyfin DB Monitor" -Action $action -Trigger $trigger

.NOTES
    Author: Generated for Jellyfin PostgreSQL Project
    Date: 2026-03-05
#>

[CmdletBinding()]
param (
    [Parameter()]
    [string]$OutputDirectory = "reports\weekly",

    [Parameter()]
    [switch]$EmailReport,

    [Parameter()]
    [switch]$CompareWithPrevious,

    [Parameter()]
    [switch]$AutoVacuumAnalyze,

    [Parameter()]
    [ValidateRange(1, [int]::MaxValue)]
    [int]$DeadTupleThreshold = 10000,

    [Parameter()]
    [ValidateRange(0.01, 100.0)]
    [double]$DeadTuplePercentThreshold = 20.0
)

# ============================================================================
# Configuration
# ============================================================================

$ErrorActionPreference = "Stop"
$ScriptRoot = Split-Path -Parent $PSCommandPath
$ProjectRoot = Split-Path -Parent $ScriptRoot

# Load database configuration
. "$ProjectRoot\scripts\db-config.ps1"

# ============================================================================
# Functions
# ============================================================================

function Write-ColorOutput {
    param(
        [string]$Message,
        [ConsoleColor]$Color = 'White'
    )
    Write-Host $Message -ForegroundColor $Color
}

function Get-ReportTimestamp {
    return Get-Date -Format "yyyy-MM-dd_HHmmss"
}

function Get-WeekNumber {
    $date = Get-Date
    $culture = [System.Globalization.CultureInfo]::CurrentCulture
    return $culture.Calendar.GetWeekOfYear($date, 
        [System.Globalization.CalendarWeekRule]::FirstDay, 
        [DayOfWeek]::Monday)
}

function Test-DatabaseConnection {
    Write-ColorOutput "`nTesting database connection..." -Color Cyan
    
    try {
        $result = & $PSQL_PATH -h $DB_HOST -p $DB_PORT -U $DB_USER -d $DB_NAME -c "SELECT version();" 2>&1
        
        if ($LASTEXITCODE -eq 0) {
            Write-ColorOutput "[OK] Database connection successful" -Color Green
            return $true
        } else {
            Write-ColorOutput "[ERROR] Database connection failed: $result" -Color Red
            return $false
        }
    } catch {
        Write-ColorOutput "[ERROR] Database connection error: $_" -Color Red
        return $false
    }
}

function Invoke-DiagnosticReport {
    param([string]$OutputFile)
    
    Write-ColorOutput "`nRunning comprehensive diagnostics..." -Color Cyan
    
    try {
        & $PSQL_PATH -h $DB_HOST -p $DB_PORT -U $DB_USER -d $DB_NAME -f "$ProjectRoot\sql\diagnostics.sql" > $OutputFile 2>&1
        
        if ($LASTEXITCODE -eq 0) {
            Write-ColorOutput "[OK] Diagnostics completed: $OutputFile" -Color Green
            return $true
        } else {
            Write-ColorOutput "[WARN] Diagnostics completed with warnings" -Color Yellow
            return $true
        }
    } catch {
        Write-ColorOutput "[ERROR] Diagnostics failed: $_" -Color Red
        return $false
    }
}

function Invoke-QueryAnalysis {
    param([string]$OutputFile)
    
    Write-ColorOutput "`nAnalyzing slow queries..." -Color Cyan
    
    try {
        & $PSQL_PATH -h $DB_HOST -p $DB_PORT -U $DB_USER -d $DB_NAME -f "$ProjectRoot\sql\query-analysis.sql" > $OutputFile 2>&1
        
        if ($LASTEXITCODE -eq 0) {
            Write-ColorOutput "[OK] Query analysis completed: $OutputFile" -Color Green
            return $true
        } else {
            Write-ColorOutput "[WARN] Query analysis completed with warnings" -Color Yellow
            return $true
        }
    } catch {
        Write-ColorOutput "[ERROR] Query analysis failed: $_" -Color Red
        return $false
    }
}

function Get-IndexUsageStats {
    param([string]$OutputFile)
    
    Write-ColorOutput "`nGathering index usage statistics..." -Color Cyan
    
    $query = @"
SELECT 
    schemaname,
    tablename,
    indexname,
    idx_scan,
    idx_tup_read,
    idx_tup_fetch,
    pg_size_pretty(pg_relation_size(indexrelid)) AS index_size
FROM pg_stat_user_indexes
WHERE schemaname IN ('library', 'users', 'authentication', 'displaypreferences', 'activitylog')
ORDER BY schemaname, tablename, idx_scan DESC;
"@

    try {
        & $PSQL_PATH -h $DB_HOST -p $DB_PORT -U $DB_USER -d $DB_NAME -c $query > $OutputFile 2>&1
        
        if ($LASTEXITCODE -eq 0) {
            Write-ColorOutput "[OK] Index stats gathered: $OutputFile" -Color Green
            return $true
        } else {
            Write-ColorOutput "[WARN] Index stats completed with warnings" -Color Yellow
            return $true
        }
    } catch {
        Write-ColorOutput "[ERROR] Index stats failed: $_" -Color Red
        return $false
    }
}

function Get-TableSizeStats {
    param([string]$OutputFile)
    
    Write-ColorOutput "`nGathering table size statistics..." -Color Cyan
    
    $query = @"
SELECT 
    schemaname,
    tablename,
    pg_size_pretty(pg_total_relation_size(schemaname||'.'||tablename)) AS total_size,
    pg_size_pretty(pg_relation_size(schemaname||'.'||tablename)) AS table_size,
    pg_size_pretty(pg_total_relation_size(schemaname||'.'||tablename) - pg_relation_size(schemaname||'.'||tablename)) AS index_size,
    n_live_tup AS row_count,
    n_dead_tup AS dead_rows,
    ROUND(100.0 * n_dead_tup / NULLIF(n_live_tup, 0), 2) AS dead_pct
FROM pg_stat_user_tables
WHERE schemaname IN ('library', 'users', 'authentication', 'displaypreferences', 'activitylog')
ORDER BY pg_total_relation_size(schemaname||'.'||tablename) DESC;
"@

    try {
        & $PSQL_PATH -h $DB_HOST -p $DB_PORT -U $DB_USER -d $DB_NAME -c $query > $OutputFile 2>&1
        
        if ($LASTEXITCODE -eq 0) {
            Write-ColorOutput "[OK] Table size stats gathered: $OutputFile" -Color Green
            return $true
        } else {
            Write-ColorOutput "[WARN] Table size stats completed with warnings" -Color Yellow
            return $true
        }
    } catch {
        Write-ColorOutput "[ERROR] Table size stats failed: $_" -Color Red
        return $false
    }
}

function Invoke-ConditionalVacuumAnalyze {
    param(
        [int]$MinDeadTuples,
        [double]$MinDeadPercent
    )

    Write-ColorOutput "`nChecking for tables that need VACUUM ANALYZE..." -Color Cyan
    Write-ColorOutput "Thresholds: dead tuples >= $MinDeadTuples and dead percent >= $MinDeadPercent" -Color Gray

    $tableQuery = @"
SELECT
    format('%I.%I', schemaname, tablename) AS qualified_table,
    n_dead_tup,
    ROUND(100.0 * n_dead_tup / NULLIF(n_live_tup, 0), 2) AS dead_pct
FROM pg_stat_user_tables
WHERE schemaname IN ('library', 'users', 'authentication', 'displaypreferences', 'activitylog')
  AND n_live_tup > 0
  AND n_dead_tup >= $MinDeadTuples
  AND (100.0 * n_dead_tup / NULLIF(n_live_tup, 0)) >= $MinDeadPercent
ORDER BY n_dead_tup DESC;
"@

    try {
        $tables = & $PSQL_PATH -h $DB_HOST -p $DB_PORT -U $DB_USER -d $DB_NAME -t -A -F "|" -c $tableQuery 2>&1
        if ($LASTEXITCODE -ne 0) {
            Write-ColorOutput "[ERROR] Failed to evaluate dead tuple thresholds: $tables" -Color Red
            return $false
        }

        $tableLines = @($tables | Where-Object { -not [string]::IsNullOrWhiteSpace($_) })
        if ($tableLines.Count -eq 0) {
            Write-ColorOutput "[OK] No tables exceeded dead tuple thresholds" -Color Green
            return $true
        }

        Write-ColorOutput "Found $($tableLines.Count) table(s) requiring VACUUM ANALYZE" -Color Yellow

        foreach ($line in $tableLines) {
            $parts = $line -split "\|", 3
            $qualifiedTable = $parts[0].Trim()
            $deadTuples = if ($parts.Count -ge 2) { $parts[1].Trim() } else { "unknown" }
            $deadPercent = if ($parts.Count -ge 3) { $parts[2].Trim() } else { "unknown" }

            Write-ColorOutput "Running VACUUM ANALYZE on $qualifiedTable (dead tuples: $deadTuples, dead percent: $deadPercent)" -Color Cyan

            $vacuumResult = & $PSQL_PATH -h $DB_HOST -p $DB_PORT -U $DB_USER -d $DB_NAME -c "VACUUM (ANALYZE, VERBOSE) $qualifiedTable;" 2>&1
            if ($LASTEXITCODE -ne 0) {
                Write-ColorOutput "[ERROR] VACUUM ANALYZE failed for $qualifiedTable: $vacuumResult" -Color Red
                return $false
            }

            Write-ColorOutput "[OK] VACUUM ANALYZE completed for $qualifiedTable" -Color Green
        }

        return $true
    } catch {
        Write-ColorOutput "[ERROR] Conditional VACUUM ANALYZE failed: $_" -Color Red
        return $false
    }
}

function Compare-WithPrevious {
    param(
        [string]$CurrentReport,
        [string]$OutputDirectory
    )
    
    Write-ColorOutput "`nComparing with previous week's report..." -Color Cyan
    
    # Find most recent previous report
    $previousReports = Get-ChildItem "$OutputDirectory\diagnostics_*.txt" -ErrorAction SilentlyContinue |
        Where-Object { $_.Name -ne (Split-Path $CurrentReport -Leaf) } |
        Sort-Object LastWriteTime -Descending
    
    if ($previousReports.Count -eq 0) {
        Write-ColorOutput "[WARN] No previous reports found for comparison" -Color Yellow
        return
    }
    
    $previousReport = $previousReports[0].FullName
    Write-ColorOutput "Comparing with: $($previousReports[0].Name)" -Color Cyan
    
    # TODO: Add detailed comparison logic
    # For now, just note that both reports exist
    Write-ColorOutput "[OK] Comparison data available" -Color Green
    Write-ColorOutput "   Current:  $CurrentReport" -Color Gray
    Write-ColorOutput "   Previous: $previousReport" -Color Gray
}

function New-SummaryReport {
    param(
        [string]$OutputDirectory,
        [string]$Timestamp
    )
    
    Write-ColorOutput "`nGenerating summary report..." -Color Cyan
    
    $summaryFile = Join-Path $OutputDirectory "summary_$Timestamp.txt"
    
    $summary = @"
================================================================================
JELLYFIN DATABASE WEEKLY PERFORMANCE SUMMARY
================================================================================
Report Date: $(Get-Date -Format "yyyy-MM-dd HH:mm:ss")
Database: $DB_NAME at $DB_HOST
Week Number: $(Get-WeekNumber)
================================================================================

REPORTS GENERATED:
 * diagnostics_$Timestamp.txt           : Full diagnostic report
 * query_analysis_$Timestamp.txt        : Slow query analysis
 * index_usage_$Timestamp.txt           : Index usage statistics
 * table_sizes_$Timestamp.txt           : Table size and bloat info
 * summary_$Timestamp.txt               : This summary

================================================================================
QUICK HEALTH CHECK:
================================================================================

To view critical issues check diagnostics file for:
 * Section 5: TABLES WITH HIGH SEQUENTIAL SCANS
 * Section 8: UNUSED OR RARELY USED INDEXES
 * Section 10: SLOWEST QUERIES

To identify slow queries check query_analysis file for:
 * Section 2: TOP 20 SLOWEST QUERIES (by max execution time)
 * Section 5: BASEITEMS TABLE QUERIES ANALYSIS

================================================================================
RECOMMENDED ACTIONS:
================================================================================

 * Review slow queries taking longer than 10 seconds
 * Check if new indexes are being utilized
 * Look for tables with many sequential scans
 * Monitor cache hit ratio (should be above 95 percent)
 * Check for tables with high dead tuples percentage (need VACUUM)

================================================================================
AUTOMATION SETUP:
================================================================================

To schedule this script weekly via Task Scheduler run Setup-Weekly-Monitor.ps1
as Administrator. This will create a scheduled task to run every Monday at 6am.

To disable the scheduled task run Setup-Weekly-Monitor.ps1 with -Uninstall flag.

================================================================================
NEXT REPORT: $(Get-Date).AddDays(7).ToString("yyyy-MM-dd")
================================================================================
"@

    $summary | Out-File -FilePath $summaryFile -Encoding UTF8
    Write-ColorOutput "[OK] Summary generated: $summaryFile" -Color Green
}

# ============================================================================
# Main Execution
# ============================================================================

Write-ColorOutput "`n========================================" -Color Cyan
Write-ColorOutput "Jellyfin Database Weekly Monitor" -Color Cyan
Write-ColorOutput "========================================" -Color Cyan
Write-ColorOutput "Database: $DB_NAME" -Color Yellow
Write-ColorOutput "Host: $DB_HOST" -Color Yellow
Write-ColorOutput "Week: $(Get-WeekNumber)" -Color Yellow
Write-ColorOutput "Date: $(Get-Date -Format 'yyyy-MM-dd HH:mm:ss')" -Color Yellow
Write-ColorOutput "========================================`n" -Color Cyan

# Create output directory
$reportDir = Join-Path $ProjectRoot $OutputDirectory
if (-not (Test-Path $reportDir)) {
    New-Item -ItemType Directory -Path $reportDir -Force | Out-Null
    Write-ColorOutput "Created report directory: $reportDir" -Color Green
}

# Generate timestamp for this run
$timestamp = Get-ReportTimestamp

# Test connection
if (-not (Test-DatabaseConnection)) {
    Write-ColorOutput "`n[ERROR] Cannot connect to database. Exiting." -Color Red
    exit 1
}

# Run diagnostics
$diagnosticsFile = Join-Path $reportDir "diagnostics_$timestamp.txt"
$success = Invoke-DiagnosticReport -OutputFile $diagnosticsFile

if (-not $success) {
    Write-ColorOutput "`n[WARN] Some reports failed. Check output directory." -Color Yellow
}

# Run query analysis
$queryAnalysisFile = Join-Path $reportDir "query_analysis_$timestamp.txt"
Invoke-QueryAnalysis -OutputFile $queryAnalysisFile | Out-Null

# Gather index usage stats
$indexUsageFile = Join-Path $reportDir "index_usage_$timestamp.txt"
Get-IndexUsageStats -OutputFile $indexUsageFile | Out-Null

# Gather table size stats
$tableSizesFile = Join-Path $reportDir "table_sizes_$timestamp.txt"
Get-TableSizeStats -OutputFile $tableSizesFile | Out-Null

# Optionally vacuum/analyze tables that exceed dead tuple thresholds
if ($AutoVacuumAnalyze) {
    $vacuumSuccess = Invoke-ConditionalVacuumAnalyze `
        -MinDeadTuples $DeadTupleThreshold `
        -MinDeadPercent $DeadTuplePercentThreshold

    if (-not $vacuumSuccess) {
        Write-ColorOutput "[WARN] Conditional VACUUM ANALYZE encountered errors" -Color Yellow
    }
}

# Compare with previous week if requested
if ($CompareWithPrevious) {
    Compare-WithPrevious -CurrentReport $diagnosticsFile -OutputDirectory $reportDir
}

# Generate summary
New-SummaryReport -OutputDirectory $reportDir -Timestamp $timestamp

# Cleanup old reports (keep last 12 weeks)
Write-ColorOutput "`nCleaning up old reports (keeping last 12 weeks)..." -Color Cyan
Get-ChildItem $reportDir -File | 
    Where-Object { $_.LastWriteTime -lt (Get-Date).AddDays(-84) } |
    Remove-Item -Force
Write-ColorOutput "[OK] Cleanup complete" -Color Green

Write-ColorOutput "`n========================================" -Color Green
Write-ColorOutput "[OK] WEEKLY MONITORING COMPLETE" -Color Green
Write-ColorOutput "========================================" -Color Green
Write-ColorOutput "Reports saved to: $reportDir" -Color Yellow
Write-ColorOutput "Summary: summary_$timestamp.txt" -Color Yellow
Write-ColorOutput "`nNext steps:" -Color Cyan
Write-ColorOutput "1. Review summary_$timestamp.txt" -Color White
Write-ColorOutput "2. Check for critical issues in diagnostics report" -Color White
Write-ColorOutput "3. Analyze slow queries in query_analysis report" -Color White
Write-ColorOutput "========================================`n" -Color Green

# Email report if requested (placeholder)
if ($EmailReport) {
    Write-ColorOutput "[WARN] Email functionality not yet implemented" -Color Yellow
    Write-ColorOutput "   Configure Send-MailMessage with your SMTP settings" -Color Gray
}

exit 0