// Copyright 2014 The Gogs Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.

package process

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"os/exec"
	"sync"
	"time"
)

// TODO: This packages still uses a singleton for the Manager.
// Once there's a decent web framework and dependencies are passed around like they should,
// then we delete the singleton.

var (
	// ErrExecTimeout represent a timeout error
	ErrExecTimeout = errors.New("Process execution timeout")
	manager        *Manager
)

// Process represents a working process inherit from Gogs.
type Process struct {
	PID         int64 // Process ID, not system one.
	Description string
	Start       time.Time
	Cmd         *exec.Cmd
}

// Manager knows about all processes and counts PIDs.
type Manager struct {
	mutex sync.Mutex

	counter   int64
	Processes map[int64]*Process
}

// GetManager returns a Manager and initializes one as singleton if there's none yet
func GetManager() *Manager {
	if manager == nil {
		manager = &Manager{
			Processes: make(map[int64]*Process),
		}
	}
	return manager
}

// Add a process to the ProcessManager and returns its PID.
func (pm *Manager) Add(description string, cmd *exec.Cmd) int64 {
	pm.mutex.Lock()
	pid := pm.counter + 1
	pm.Processes[pid] = &Process{
		PID:         pid,
		Description: description,
		Start:       time.Now(),
		Cmd:         cmd,
	}
	pm.counter = pid
	pm.mutex.Unlock()

	return pid
}

// Remove a process from the ProcessManager.
func (pm *Manager) Remove(pid int64) {
	pm.mutex.Lock()
	delete(pm.Processes,