#!/usr/bin/env luash
-- Data Processing Demo: File processing, text manipulation, and analysis

print("=== Data Processing with Luash ===\n")

-- Create sample data for demonstration
print("1. Creating Sample Data:")
sample_data = [[timestamp,user,action,value
2024-01-01 10:00:00,alice,login,1
2024-01-01 10:05:00,bob,purchase,25.50
2024-01-01 10:10:00,alice,logout,1
2024-01-01 10:15:00,charlie,login,1
2024-01-01 10:20:00,bob,purchase,15.75
2024-01-01 10:25:00,charlie,purchase,45.00]]

-- Write sample data to file
local file = io.open("sample_data.csv", "w")
file:write(sample_data)
file:close()
print("   Sample CSV data created: sample_data.csv")

-- File analysis using shell commands
print("\n2. File Analysis:")
line_count = `wc -l < sample_data.csv`
print("   Total lines: " .. line_count)

file_size = `du -h sample_data.csv | cut -f1`
print("   File size: " .. file_size)

-- Data extraction and filtering
print("\n3. Data Extraction:")
print("   Purchase transactions:")
!grep "purchase" sample_data.csv

-- Using Lua for more complex processing
print("\n4. Advanced Processing with Lua:")
local data_file = io.open("sample_data.csv", "r")
local purchases = {}
local users = {}

-- Skip header line
data_file:read("*line")

-- Process each line
for line in data_file:lines() do
    local timestamp, user, action, value = line:match("([^,]+),([^,]+),([^,]+),([^,]+)")
    
    if action == "purchase" then
        table.insert(purchases, {
            timestamp = timestamp,
            user = user,
            amount = tonumber(value)
        })
    end
    
    users[user] = true
end
data_file:close()

-- Calculate statistics
local total_amount = 0
local purchase_count = #purchases
for i = 1, purchase_count do
    total_amount = total_amount + purchases[i].amount
end

local user_count = 0
for user, _ in pairs(users) do
    user_count = user_count + 1
end

print("   Statistics:")
print("   - Total users: " .. user_count)
print("   - Total purchases: " .. purchase_count)
print("   - Total revenue: $" .. string.format("%.2f", total_amount))
print("   - Average purchase: $" .. string.format("%.2f", total_amount / purchase_count))

-- Log file processing
print("\n5. Log Processing:")
log_content = `tail -20 /var/log/system.log 2>/dev/null || echo "Log not accessible"`
if log_content ~= "Log not accessible" then
    print("   Recent system log entries found")
else
    -- Create a sample log for demonstration
    sample_log = [[2024-01-01 10:00:01 INFO: Application started
2024-01-01 10:00:05 DEBUG: Database connection established
2024-01-01 10:00:10 WARN: High memory usage detected
2024-01-01 10:00:15 ERROR: Failed to connect to external API
2024-01-01 10:00:20 INFO: Retrying API connection
2024-01-01 10:00:25 INFO: API connection restored]]
    
    local log_file = io.open("sample.log", "w")
    log_file:write(sample_log)
    log_file:close()
    
    print("   Created sample.log for demonstration")
    print("   Log analysis:")
    
    -- Count log levels
    error_count = `grep -c "ERROR" sample.log`
    warn_count = `grep -c "WARN" sample.log`
    info_count = `grep -c "INFO" sample.log`
    
    print("   - Errors: " .. error_count)
    print("   - Warnings: " .. warn_count)
    print("   - Info messages: " .. info_count)
end

-- Text transformation
print("\n6. Text Transformation:")
input_text = "Hello World, this is a TEST message"

-- Using shell commands for text processing
upper_text = `echo "` .. input_text .. `" | tr '[:lower:]' '[:upper:]'`
print("   Uppercase: " .. upper_text)

word_count = `echo "` .. input_text .. `" | wc -w`
print("   Word count: " .. word_count)

-- Using Lua for more complex transformations
words = {}
for word in input_text:gmatch("%w+") do
    table.insert(words, word)
end

print("   Words: " .. table.concat(words, ", "))
print("   Reversed: " .. table.concat(words, " "):reverse())

-- Batch file processing
print("\n7. Batch Processing:")
-- Create multiple sample files
for i = 1, 3 do
    local batch_file = io.open("batch_" .. i .. ".txt", "w")
    batch_file:write("Sample content for file " .. i .. "\n")
    batch_file:write("Line 2 of file " .. i .. "\n")
    batch_file:close()
end

print("   Created 3 batch files")

-- Process all batch files
batch_files = `ls batch_*.txt`
total_lines = 0

for filename in batch_files:gmatch("[^\n]+") do
    local lines = `wc -l < ` .. filename
    total_lines = total_lines + tonumber(lines)
    print("   " .. filename .. ": " .. lines .. " lines")
end

print("   Total lines across all files: " .. total_lines)

-- Cleanup
print("\n8. Cleanup:")
!rm -f sample_data.csv sample.log batch_*.txt
print("   Temporary files cleaned up")

print("\n✓ Data processing demo completed!")