// Copyright 2018 gf Author(https://gitee.com/johng/gf). All Rights Reserved.
//
// This Source Code Form is subject to the terms of the MIT License.
// If a copy of the MIT was not distributed with this file,
// You can obtain one at https://gitee.com/johng/gf.

package gproc

import (
    "os"
    "fmt"
    "os/exec"
    "errors"
    "strings"
)

// 子进程
type Process struct {
    exec.Cmd
    Manager     *Manager // 所属进程管理器
    PPid        int      // 自定义关联的父进程ID
}

// 创建一个进程(不执行)
func NewProcess(path string, args []string, environment...[]string) *Process {
    var env []string
    if len(environment) > 0 {
        env = make([]string, 0)
        for _, v := range environment[0] {
            env = append(env, v)
        }
    } else {
        env = os.Environ()
    }
    env= append(env, fmt.Sprintf("%s=%s", gPROC_TEMP_DIR_ENV_KEY, os.TempDir()))
    p := &Process {
        Manager     : nil,
        PPid        : os.Getpid(),
        Cmd         : exec.Cmd {
            Args       : []string{path},
            Path       : path,
            Stdin      : os.Stdin,
            Stdout     : os.Stdout,
            Stderr     : os.Stderr,
            Env        : env,
            ExtraFiles : make([]*os.File, 0),
        },
    }
    // 当前工作目录
    if d, err := os.Getwd(); err == nil {
        p.Dir = d
    }
    if len(args) > 0 {
        start := 0
        if strings.EqualFold(path, args[0]) {
            start = 1
        }
        p.Args = append(p.Args, args[start : ]...)
    }
    return p
}

// 开始执行(非阻塞)
func (p *Process) Start() (int, error) {
    if p.Process != nil {
        return p.Pid(), nil
    }
    p.Env = append(p.Env, fmt.Sprintf("%s=%d", gPROC_ENV_KEY_PPID_KEY, p.PPid))
    if err := p.Cmd.Start(); err == nil {
        if p.Manager != nil {
            p.Manager.processes.Set(p.Process.Pid, p)
        }
        return p.Process.Pid, nil
    } else {
        return 0, err
    }
}

// 运行进程(阻塞等待执行完毕)
func (p *Process) Run() error {
    if _, err := p.Start(); err == nil {
        return p.Wait()
    } else {
        return err
    }
}

// PID
func (p *Process) Pid() int {
    if p.Process != nil {
        return p.Process.Pid
    }
    return 0
}

// 向进程发送消息
func (p *Process) Send(data []byte) error {
    if p.Process != nil {
        return Send(p.Process.Pid, data)
    }
    return errors.New("invalid process")
}


// Release releases any resources associated with the Process p,
// rendering it unusable in the future.
// Release only needs to be called if Wait is not.
func (p *Process) Release() error {
    return p.Process.Release()
}

// Kill causes the Process to exit immediately.
func (p *Process) Kill() error {
    if err := p.Process.Kill(); err == nil {
        if p.Manager != nil {
            p.Manager.processes.Remove(p.Pid())
        }
        return nil
    } else {
        return err
    }
}

// Signal sends a signal to the Process.
// Sending Interrupt on Windows is not implemented.
func (p *Process) Signal(sig os.Signal) error {
    return p.Process.Signal(sig)
}