package sign

import (
	"fmt"
	"github.com/samber/lo"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"
)

type ProcessStatus = int8

const (
	ProcessCreated = ProcessStatus(iota)
	ProcessStarting
	ProcessStarted
	ProcessExited
	ProcessFailure
)

type ProcessInstance struct {
	ID          string     `json:"id" yaml:"id"`
	Workdir     string     `json:"workdir" yaml:"workdir"`
	Command     []string   `json:"command" yaml:"command"`
	Environment []string   `json:"environment" yaml:"environment"`
	Prepares    [][]string `json:"prepares" yaml:"prepares"`
	Preheat     bool       `json:"preheat" yaml:"preheat"`

	Cmd    *exec.Cmd       `json:"-"`
	Logger strings.Builder `json:"-"`

	Status ProcessStatus `json:"status"`
}

func (v *ProcessInstance) BootProcess() error {
	if v.Cmd != nil {
		return nil
	}
	if err := v.PrepareProcess(); err != nil {
		return err
	}
	if v.Cmd == nil {
		return v.StartProcess()
	}
	if v.Cmd.Process == nil || v.Cmd.ProcessState == nil {
		return v.StartProcess()
	}
	if v.Cmd.ProcessState.Exited() {
		return v.StartProcess()
	} else if v.Cmd.ProcessState.Exited() {
		return fmt.Errorf("process already dead")
	}
	if v.Cmd.ProcessState.Exited() {
		return fmt.Errorf("cannot start process")
	} else {
		return nil
	}
}

func (v *ProcessInstance) PrepareProcess() error {
	for _, script := range v.Prepares {
		if len(script) <= 0 {
			continue
		}
		cmd := exec.Command(script[0], script[1:]...)
		cmd.Dir = filepath.Join(v.Workdir)
		if err := cmd.Run(); err != nil {
			return err
		}
	}
	return nil
}

func (v *ProcessInstance) StartProcess() error {
	if len(v.Command) <= 0 {
		return fmt.Errorf("you need set the command for %s to enable process manager", v.ID)
	}

	v.Cmd = exec.Command(v.Command[0], v.Command[1:]...)
	v.Cmd.Dir = filepath.Join(v.Workdir)
	v.Cmd.Env = append(v.Cmd.Env, v.Environment...)
	v.Cmd.Stdout = &v.Logger
	v.Cmd.Stderr = &v.Logger

	// Monitor
	go func() {
		for {
			if v.Cmd.Process == nil || v.Cmd.ProcessState == nil {
				v.Status = ProcessStarting
			} else if !v.Cmd.ProcessState.Exited() {
				v.Status = ProcessStarted
			} else {
				v.Status = lo.Ternary(v.Cmd.ProcessState.Success(), ProcessExited, ProcessFailure)
				return
			}
			time.Sleep(100 * time.Millisecond)
		}
	}()

	return v.Cmd.Start()
}

func (v *ProcessInstance) StopProcess() error {
	if v.Cmd != nil && v.Cmd.Process != nil {
		if err := v.Cmd.Process.Signal(os.Interrupt); err != nil {
			v.Cmd.Process.Kill()
			return err
		} else {
			v.Cmd = nil
		}
	}

	return nil
}

func (v *ProcessInstance) GetLogs() string {
	return v.Logger.String()
}

func (v *RoadApp) PreheatProcesses(callbacks ...func(total int, success int)) {
	var processes []*ProcessInstance
	for _, site := range v.Sites {
		for _, process := range site.Processes {
			if process.Preheat {
				processes = append(processes, process)
			}
		}
	}

	success := 0
	for _, process := range processes {
		if process.BootProcess() == nil {
			success++
		}
	}

	if len(callbacks) > 0 {
		for _, callback := range callbacks {
			callback(len(processes), success)
		}
	}
}