package executils

import (
	"bufio"
	"errors"
	"fmt"
	"os"
	"os/exec"
	"sync"
	"time"

	"jiggablend/pkg/types"
)

// DefaultTracker is the global default process tracker
// Use this for processes that should be tracked globally and killed on shutdown
var DefaultTracker = NewProcessTracker()

// ProcessTracker tracks running processes for cleanup
type ProcessTracker struct {
	processes sync.Map // map[int64]*exec.Cmd - tracks running processes by task ID
}

// NewProcessTracker creates a new process tracker
func NewProcessTracker() *ProcessTracker {
	return &ProcessTracker{}
}

// Track registers a process for tracking
func (pt *ProcessTracker) Track(taskID int64, cmd *exec.Cmd) {
	pt.processes.Store(taskID, cmd)
}

// Untrack removes a process from tracking
func (pt *ProcessTracker) Untrack(taskID int64) {
	pt.processes.Delete(taskID)
}

// Get returns the command for a task ID if it exists
func (pt *ProcessTracker) Get(taskID int64) (*exec.Cmd, bool) {
	if val, ok := pt.processes.Load(taskID); ok {
		return val.(*exec.Cmd), true
	}
	return nil, false
}

// Kill kills a specific process by task ID
// Returns true if the process was found and killed
func (pt *ProcessTracker) Kill(taskID int64) bool {
	cmd, ok := pt.Get(taskID)
	if !ok || cmd.Process == nil {
		return false
	}

	// Try graceful kill first (SIGINT)
	if err := cmd.Process.Signal(os.Interrupt); err != nil {
		// If SIGINT fails, try SIGKILL
		cmd.Process.Kill()
	} else {
		// Give it a moment to clean up gracefully
		time.Sleep(100 * time.Millisecond)
		// Force kill if still running
		cmd.Process.Kill()
	}

	pt.Untrack(taskID)
	return true
}

// KillAll kills all tracked processes
// Returns the number of processes killed
func (pt *ProcessTracker) KillAll() int {
	var killedCount int
	pt.processes.Range(func(key, value interface{}) bool {
		taskID := key.(int64)
		cmd := value.(*exec.Cmd)
		if cmd.Process != nil {
			// Try graceful kill first (SIGINT)
			if err := cmd.Process.Signal(os.Interrupt); err == nil {
				// Give it a moment to clean up
				time.Sleep(100 * time.Millisecond)
			}
			// Force kill
			cmd.Process.Kill()
			killedCount++
		}
		pt.processes.Delete(taskID)
		return true
	})
	return killedCount
}

// Count returns the number of tracked processes
func (pt *ProcessTracker) Count() int {
	count := 0
	pt.processes.Range(func(key, value interface{}) bool {
		count++
		return true
	})
	return count
}

// CommandResult holds the output from a command execution
type CommandResult struct {
	Stdout   string
	Stderr   string
	ExitCode int
}

// RunCommand executes a command and returns the output
// If tracker is provided, the process will be registered for tracking
// This is useful for commands where you need to capture output (like metadata extraction)
func RunCommand(
	cmdPath string,
	args []string,
	dir string,
	env []string,
	taskID int64,
	tracker *ProcessTracker,
) (*CommandResult, error) {
	cmd := exec.Command(cmdPath, args...)
	cmd.Dir = dir
	if env != nil {
		cmd.Env = env
	}

	stdoutPipe, err := cmd.StdoutPipe()
	if err != nil {
		return nil, fmt.Errorf("failed to create stdout pipe: %w", err)
	}

	stderrPipe, err := cmd.StderrPipe()
	if err != nil {
		return nil, fmt.Errorf("failed to create stderr pipe: %w", err)
	}

	if err := cmd.Start(); err != nil {
		return nil, fmt.Errorf("failed to start command: %w", err)
	}

	// Track the process if tracker is provided
	if tracker != nil {
		tracker.Track(taskID, cmd)
		defer tracker.Untrack(taskID)
	}

	// Collect stdout
	var stdoutBuf, stderrBuf []byte
	var stdoutErr, stderrErr error
	var wg sync.WaitGroup
	wg.Add(2)

	go func() {
		defer wg.Done()
		stdoutBuf, stdoutErr = readAll(stdoutPipe)
	}()

	go func() {
		defer wg.Done()
		stderrBuf, stderrErr = readAll(stderrPipe)
	}()

	waitErr := cmd.Wait()
	wg.Wait()

	// Check for read errors
	if stdoutErr != nil {
		return nil, fmt.Errorf("failed to read stdout: %w", stdoutErr)
	}
	if stderrErr != nil {
		return nil, fmt.Errorf("failed to read stderr: %w", stderrErr)
	}

	result := &CommandResult{
		Stdout: string(stdoutBuf),
		Stderr: string(stderrBuf),
	}

	if waitErr != nil {
		if exitErr, ok := waitErr.(*exec.ExitError); ok {
			result.ExitCode = exitErr.ExitCode()
		} else {
			result.ExitCode = -1
		}
		return result, waitErr
	}

	result.ExitCode = 0
	return result, nil
}

// readAll reads all data from a reader
func readAll(r interface{ Read([]byte) (int, error) }) ([]byte, error) {
	var buf []byte
	tmp := make([]byte, 4096)
	for {
		n, err := r.Read(tmp)
		if n > 0 {
			buf = append(buf, tmp[:n]...)
		}
		if err != nil {
			if err.Error() == "EOF" {
				break
			}
			return buf, err
		}
	}
	return buf, nil
}

// LogSender is a function type for sending logs
type LogSender func(taskID int, level types.LogLevel, message string, stepName string)

// LineFilter is a function that processes a line and returns whether to filter it out and the log level
type LineFilter func(line string) (shouldFilter bool, level types.LogLevel)

// RunCommandWithStreaming executes a command with streaming output and OOM detection
// If tracker is provided, the process will be registered for tracking
func RunCommandWithStreaming(
	cmdPath string,
	args []string,
	dir string,
	env []string,
	taskID int,
	stepName string,
	logSender LogSender,
	stdoutFilter LineFilter,
	stderrFilter LineFilter,
	oomMessage string,
	tracker *ProcessTracker,
) error {
	cmd := exec.Command(cmdPath, args...)
	cmd.Dir = dir
	cmd.Env = env

	stdoutPipe, err := cmd.StdoutPipe()
	if err != nil {
		errMsg := fmt.Sprintf("failed to create stdout pipe: %v", err)
		logSender(taskID, types.LogLevelError, errMsg, stepName)
		return errors.New(errMsg)
	}

	stderrPipe, err := cmd.StderrPipe()
	if err != nil {
		errMsg := fmt.Sprintf("failed to create stderr pipe: %v", err)
		logSender(taskID, types.LogLevelError, errMsg, stepName)
		return errors.New(errMsg)
	}

	if err := cmd.Start(); err != nil {
		errMsg := fmt.Sprintf("failed to start command: %v", err)
		logSender(taskID, types.LogLevelError, errMsg, stepName)
		return errors.New(errMsg)
	}

	// Track the process if tracker is provided
	if tracker != nil {
		tracker.Track(int64(taskID), cmd)
		defer tracker.Untrack(int64(taskID))
	}

	var wg sync.WaitGroup
	wg.Add(2)

	go func() {
		defer wg.Done()
		scanner := bufio.NewScanner(stdoutPipe)
		for scanner.Scan() {
			line := scanner.Text()
			if line != "" {
				shouldFilter, level := stdoutFilter(line)
				if !shouldFilter {
					logSender(taskID, level, line, stepName)
				}
			}
		}
	}()

	go func() {
		defer wg.Done()
		scanner := bufio.NewScanner(stderrPipe)
		for scanner.Scan() {
			line := scanner.Text()
			if line != "" {
				shouldFilter, level := stderrFilter(line)
				if !shouldFilter {
					logSender(taskID, level, line, stepName)
				}
			}
		}
	}()

	err = cmd.Wait()
	wg.Wait()

	if err != nil {
		var errMsg string
		if exitErr, ok := err.(*exec.ExitError); ok {
			if exitErr.ExitCode() == 137 {
				errMsg = oomMessage
			} else {
				errMsg = fmt.Sprintf("command failed: %v", err)
			}
		} else {
			errMsg = fmt.Sprintf("command failed: %v", err)
		}
		logSender(taskID, types.LogLevelError, errMsg, stepName)
		return errors.New(errMsg)
	}

	return nil
}

// ============================================================================
// Helper functions using DefaultTracker
// ============================================================================

// Run executes a command using the default tracker and returns the output
// This is a convenience wrapper around RunCommand that uses DefaultTracker
func Run(cmdPath string, args []string, dir string, env []string, taskID int64) (*CommandResult, error) {
	return RunCommand(cmdPath, args, dir, env, taskID, DefaultTracker)
}

// RunStreaming executes a command with streaming output using the default tracker
// This is a convenience wrapper around RunCommandWithStreaming that uses DefaultTracker
func RunStreaming(
	cmdPath string,
	args []string,
	dir string,
	env []string,
	taskID int,
	stepName string,
	logSender LogSender,
	stdoutFilter LineFilter,
	stderrFilter LineFilter,
	oomMessage string,
) error {
	return RunCommandWithStreaming(cmdPath, args, dir, env, taskID, stepName, logSender, stdoutFilter, stderrFilter, oomMessage, DefaultTracker)
}

// KillAll kills all processes tracked by the default tracker
// Returns the number of processes killed
func KillAll() int {
	return DefaultTracker.KillAll()
}

// Kill kills a specific process by task ID using the default tracker
// Returns true if the process was found and killed
func Kill(taskID int64) bool {
	return DefaultTracker.Kill(taskID)
}

// Track registers a process with the default tracker
func Track(taskID int64, cmd *exec.Cmd) {
	DefaultTracker.Track(taskID, cmd)
}

// Untrack removes a process from the default tracker
func Untrack(taskID int64) {
	DefaultTracker.Untrack(taskID)
}

// GetTrackedCount returns the number of processes tracked by the default tracker
func GetTrackedCount() int {
	return DefaultTracker.Count()
}