package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"os/signal"
	"path/filepath"
	"plugin"
	"strconv"
	"strings"
	"syscall"
	"time"

	docopt "github.com/docopt/docopt.go"
	ui "github.com/gizak/termui/v3"
	"github.com/prometheus/client_golang/prometheus/promhttp"

	"github.com/xxxserxxx/gotop/v3"
	"github.com/xxxserxxx/gotop/v3/colorschemes"
	"github.com/xxxserxxx/gotop/v3/layout"
	"github.com/xxxserxxx/gotop/v3/logging"
	"github.com/xxxserxxx/gotop/v3/utils"
	w "github.com/xxxserxxx/gotop/v3/widgets"
)

const (
	appName = "gotop"

	graphHorizontalScaleDelta = 3
	defaultUI                 = "2:cpu\ndisk/1 2:mem/2\ntemp\n2:net 2:procs"
	minimalUI                 = "cpu\nmem procs"
	batteryUI                 = "cpu/2 batt/1\ndisk/1 2:mem/2\ntemp\nnet procs"
	procsUI                   = "cpu 4:procs\ndisk\nmem\nnet"
	kitchensink               = "3:cpu/2 3:mem/1\n4:temp/1 3:disk/2\npower\n3:net 3:procs"
)

var (
	// TODO: Set this at compile time; having to check this in sucks.
	Version      = "3.5.2"
	conf         gotop.Config
	help         *w.HelpMenu
	bar          *w.StatusBar
	statusbar    bool
	stderrLogger = log.New(os.Stderr, "", 0)
)

// TODO: Add tab completion for Linux https://gist.github.com/icholy/5314423
// TODO: state:merge #135 linux console font (cmatsuoka/console-font)
// TODO: state:deferred 157 FreeBSD fixes & Nvidia GPU support (kraust/master). Significant CPU use impact for NVidia changes.
// TODO: Virtual devices from Prometeus metrics @feature
// TODO: Abstract out the UI toolkit.  mum4k/termdash, VladimirMarkelov/clui, gcla/gowid, rivo/tview, marcusolsson/tui-go might work better for some OS/Archs. Performance/memory use comparison would be interesting.
func parseArgs(conf *gotop.Config) error {
	usage := `
Usage: gotop [options]

Options:
  -c, --color=NAME        Set a colorscheme.
  -h, --help              Show this screen.
  -m, --minimal           Only show CPU, Mem and Process widgets. Overrides -l. (DEPRECATED, use -l minimal)
  -r, --rate=RATE         Number of times per second to update CPU and Mem widgets [default: 1].
  -V, --version           Print version and exit.
  -p, --percpu            Show each CPU in the CPU widget.
  -a, --averagecpu        Show average CPU in the CPU widget.
  -f, --fahrenheit        Show temperatures in fahrenheit.
  -s, --statusbar         Show a statusbar with the time.
  -b, --battery           Show battery level widget ('minimal' turns off). (DEPRECATED, use -l battery)
  -B, --bandwidth=bits	  Specify the number of bits per seconds.
  -l, --layout=NAME       Name of layout spec file for the UI.  Looks first in $XDG_CONFIG_HOME/gotop, then as a path.  Use "-" to pipe.
  -i, --interface=NAME    Select network interface [default: all]. Several interfaces can be defined using comma separated values. Interfaces can also be ignored using !  
  -x, --export=PORT       Enable metrics for export on the specified port.
  -X, --extensions=NAMES  Enables the listed extensions.  This is a comma-separated list without the .so suffix. The current and config directories will be searched.  
      --test              Runs tests and exits with success/failure code  


Built-in layouts:
  default
  minimal
  battery
  kitchensink

Colorschemes:
  default
  default-dark (for white background)
  solarized
  solarized16-dark
  solarized16-light
  monokai
  vice
`

	var err error
	conf.Colorscheme, err = colorschemes.FromName(conf.ConfigDir, "default")
	if err != nil {
		return err
	}

	args, err := docopt.ParseArgs(usage, os.Args[1:], Version)
	if err != nil {
		return err
	}

	if val, _ := args["--layout"]; val != nil {
		conf.Layout = val.(string)
	}
	if val, _ := args["--color"]; val != nil {
		cs, err := colorschemes.FromName(conf.ConfigDir, val.(string))
		if err != nil {
			return err
		}
		conf.Colorscheme = cs
	}
	if args["--averagecpu"].(bool) {
		conf.AverageLoad, _ = args["--averagecpu"].(bool)
	}
	if args["--percpu"].(bool) {
		conf.PercpuLoad, _ = args["--percpu"].(bool)
	}
	if args["--statusbar"].(bool) {
		statusbar, _ = args["--statusbar"].(bool)
	}
	if args["--battery"].(bool) {
		conf.Layout = "battery"
	}
	if args["--minimal"].(bool) {
		conf.Layout = "minimal"
	}
	if val, _ := args["--export"]; val != nil {
		conf.ExportPort = val.(string)
	}
	if val, _ := args["--rate"]; val != nil {
		rateStr, _ := val.(string)
		rate, err := strconv.ParseFloat(rateStr, 64)
		if err != nil {
			return fmt.Errorf("invalid rate parameter")
		}
		if rate < 1 {
			conf.UpdateInterval = time.Second * time.Duration(1/rate)
		} else {
			conf.UpdateInterval = time.Second / time.Duration(rate)
		}
	}
	if val, _ := args["--fahrenheit"]; val != nil {
		fahrenheit, _ := val.(bool)
		if fahrenheit {
			conf.TempScale = w.Fahrenheit
		}
	}
	if val, _ := args["--interface"]; val != nil {
		conf.NetInterface, _ = args["--interface"].(string)
	}
	if val, _ := args["--extensions"]; val != nil {
		exs, _ := args["--extensions"].(string)
		conf.Extensions = strings.Split(exs, ",")
	}
	if val, _ := args["--test"]; val != nil {
		conf.Test = val.(bool)
	}

	return nil
}

func setDefaultTermuiColors(c gotop.Config) {
	ui.Theme.Default = ui.NewStyle(ui.Color(c.Colorscheme.Fg), ui.Color(c.Colorscheme.Bg))
	ui.Theme.Block.Title = ui.NewStyle(ui.Color(c.Colorscheme.BorderLabel), ui.Color(c.Colorscheme.Bg))
	ui.Theme.Block.Border = ui.NewStyle(ui.Color(c.Colorscheme.BorderLine), ui.Color(c.Colorscheme.Bg))
}

func eventLoop(c gotop.Config, grid *layout.MyGrid) {
	drawTicker := time.NewTicker(c.UpdateInterval).C

	// handles kill signal sent to gotop
	sigTerm := make(chan os.Signal, 2)
	signal.Notify(sigTerm, os.Interrupt, syscall.SIGTERM)

	uiEvents := ui.PollEvents()

	previousKey := ""

	for {
		select {
		case <-sigTerm:
			return
		case <-drawTicker:
			if !c.HelpVisible {
				ui.Render(grid)
				if statusbar {
					ui.Render(bar)
				}
			}
		case e := <-uiEvents:
			if grid.Proc != nil && grid.Proc.HandleEvent(e) {
				ui.Render(grid.Proc)
				break
			}
			switch e.ID {
			case "q", "<C-c>":
				return
			case "?":
				c.HelpVisible = !c.HelpVisible
			case "<Resize>":
				payload := e.Payload.(ui.Resize)
				termWidth, termHeight := payload.Width, payload.Height
				if statusbar {
					grid.SetRect(0, 0, termWidth, termHeight-1)
					bar.SetRect(0, termHeight-1, termWidth, termHeight)
				} else {
					grid.SetRect(0, 0, payload.Width, payload.Height)
				}
				help.Resize(payload.Width, payload.Height)
				ui.Clear()
			}

			if c.HelpVisible {
				switch e.ID {
				case "?":
					ui.Clear()
					ui.Render(help)
				case "<Escape>":
					c.HelpVisible = false
					ui.Render(grid)
				case "<Resize>":
					ui.Render(help)
				}
			} else {
				switch e.ID {
				case "?":
					ui.Render(grid)
				case "h":
					c.GraphHorizontalScale += graphHorizontalScaleDelta
					for _, item := range grid.Lines {
						item.Scale(c.GraphHorizontalScale)
					}
					ui.Render(grid)
				case "l":
					if c.GraphHorizontalScale > graphHorizontalScaleDelta {
						c.GraphHorizontalScale -= graphHorizontalScaleDelta
						for _, item := range grid.Lines {
							item.Scale(c.GraphHorizontalScale)
							ui.Render(item)
						}
					}
				case "<Resize>":
					ui.Render(grid)
					if statusbar {
						ui.Render(bar)
					}
				case "<MouseLeft>":
					if grid.Proc != nil {
						payload := e.Payload.(ui.Mouse)
						grid.Proc.HandleClick(payload.X, payload.Y)
						ui.Render(grid.Proc)
					}
				case "k", "<Up>", "<MouseWheelUp>":
					if grid.Proc != nil {
						grid.Proc.ScrollUp()
						ui.Render(grid.Proc)
					}
				case "j", "<Down>", "<MouseWheelDown>":
					if grid.Proc != nil {
						grid.Proc.ScrollDown()
						ui.Render(grid.Proc)
					}
				case "<Home>":
					if grid.Proc != nil {
						grid.Proc.ScrollTop()
						ui.Render(grid.Proc)
					}
				case "g":
					if grid.Proc != nil {
						if previousKey == "g" {
							grid.Proc.ScrollTop()
							ui.Render(grid.Proc)
						}
					}
				case "G", "<End>":
					if grid.Proc != nil {
						grid.Proc.ScrollBottom()
						ui.Render(grid.Proc)
					}
				case "<C-d>":
					if grid.Proc != nil {
						grid.Proc.ScrollHalfPageDown()
						ui.Render(grid.Proc)
					}
				case "<C-u>":
					if grid.Proc != nil {
						grid.Proc.ScrollHalfPageUp()
						ui.Render(grid.Proc)
					}
				case "<C-f>":
					if grid.Proc != nil {
						grid.Proc.ScrollPageDown()
						ui.Render(grid.Proc)
					}
				case "<C-b>":
					if grid.Proc != nil {
						grid.Proc.ScrollPageUp()
						ui.Render(grid.Proc)
					}
				case "d":
					if grid.Proc != nil {
						if previousKey == "d" {
							grid.Proc.KillProc("SIGTERM")
						}
					}
				case "3":
					if grid.Proc != nil {
						if previousKey == "d" {
							grid.Proc.KillProc("SIGQUIT")
						}
					}
				case "9":
					if grid.Proc != nil {
						if previousKey == "d" {
							grid.Proc.KillProc("SIGKILL")
						}
					}
				case "<Tab>":
					if grid.Proc != nil {
						grid.Proc.ToggleShowingGroupedProcs()
						ui.Render(grid.Proc)
					}
				case "m", "c", "p":
					if grid.Proc != nil {
						grid.Proc.ChangeProcSortMethod(w.ProcSortMethod(e.ID))
						ui.Render(grid.Proc)
					}
				case "/":
					if grid.Proc != nil {
						grid.Proc.SetEditingFilter(true)
						ui.Render(grid.Proc)
					}
				}

				if previousKey == e.ID {
					previousKey = ""
				} else {
					previousKey = e.ID
				}
			}

		}
	}
}

func makeConfig() gotop.Config {
	ld := utils.GetLogDir(appName)
	cd := utils.GetConfigDir(appName)
	conf = gotop.Config{
		ConfigDir:            cd,
		LogDir:               ld,
		LogFile:              "errors.log",
		GraphHorizontalScale: 7,
		HelpVisible:          false,
		UpdateInterval:       time.Second,
		AverageLoad:          false,
		PercpuLoad:           true,
		TempScale:            w.Celsius,
		Statusbar:            false,
		NetInterface:         w.NET_INTERFACE_ALL,
		MaxLogSize:           5000000,
		Layout:               "default",
	}
	return conf
}

// TODO: mpd visualizer widget
func main() {
	// Set up default config
	conf := makeConfig()
	// Parse the config file
	cfn := filepath.Join(conf.ConfigDir, "gotop.conf")
	if cf, err := os.Open(cfn); err == nil {
		err := gotop.Parse(cf, &conf)
		if err != nil {
			stderrLogger.Fatalf("error parsing config file %v", err)
		}
	}
	// Override with command line arguments
	err := parseArgs(&conf)
	if err != nil {
		stderrLogger.Fatalf("failed to parse cli args: %v", err)
	}

	logfile, err := logging.New(conf)
	if err != nil {
		stderrLogger.Fatalf("failed to setup log file: %v", err)
	}
	defer logfile.Close()

	lstream := getLayout(conf)
	ly := layout.ParseLayout(lstream)

	loadExtensions(conf)

	if conf.Test {
		os.Exit(runTests(conf))
	}

	if err := ui.Init(); err != nil {
		stderrLogger.Fatalf("failed to initialize termui: %v", err)
	}
	defer ui.Close()

	setDefaultTermuiColors(conf) // done before initializing widgets to allow inheriting colors
	help = w.NewHelpMenu()
	if statusbar {
		bar = w.NewStatusBar()
	}

	grid, err := layout.Layout(ly, conf)
	if err != nil {
		stderrLogger.Fatalf("failed to initialize termui: %v", err)
	}

	termWidth, termHeight := ui.TerminalDimensions()
	if statusbar {
		grid.SetRect(0, 0, termWidth, termHeight-1)
	} else {
		grid.SetRect(0, 0, termWidth, termHeight)
	}
	help.Resize(termWidth, termHeight)

	ui.Render(grid)
	if statusbar {
		bar.SetRect(0, termHeight-1, termWidth, termHeight)
		ui.Render(bar)
	}

	if conf.ExportPort != "" {
		go func() {
			http.Handle("/metrics", promhttp.Handler())
			http.ListenAndServe(conf.ExportPort, nil)
		}()
	}
	eventLoop(conf, grid)
}

func getLayout(conf gotop.Config) io.Reader {
	switch conf.Layout {
	case "-":
		return os.Stdin
	case "default":
		return strings.NewReader(defaultUI)
	case "minimal":
		return strings.NewReader(minimalUI)
	case "battery":
		return strings.NewReader(batteryUI)
	case "procs":
		return strings.NewReader(procsUI)
	case "kitchensink":
		return strings.NewReader(kitchensink)
	default:
		fp := filepath.Join(conf.ConfigDir, conf.Layout)
		fin, err := os.Open(fp)
		if err != nil {
			fin, err = os.Open(conf.Layout)
			if err != nil {
				log.Fatalf("Unable to open layout file %s or ./%s", fp, conf.Layout)
			}
		}
		return fin
	}
}

func loadExtensions(conf gotop.Config) {
	var hasError bool
	for _, ex := range conf.Extensions {
		exf := ex + ".so"
		fn := exf
		_, err := os.Stat(fn)
		if err != nil && os.IsNotExist(err) {
			log.Printf("no plugin %s found in current directory", fn)
			fn = filepath.Join(conf.ConfigDir, exf)
			_, err = os.Stat(fn)
			if err != nil || os.IsNotExist(err) {
				hasError = true
				log.Printf("no plugin %s found in config directory", fn)
				continue
			}
		}
		p, err := plugin.Open(fn)
		if err != nil {
			hasError = true
			log.Printf(err.Error())
			continue
		}
		init, err := p.Lookup("Init")
		if err != nil {
			hasError = true
			log.Printf(err.Error())
			continue
		}

		initFunc, ok := init.(func())
		if !ok {
			hasError = true
			log.Printf(err.Error())
			continue
		}
		initFunc()
	}
	if hasError {
		ui.Close()
		fmt.Printf("Error initializing requested plugins; check the log file %s\n", filepath.Join(conf.ConfigDir, conf.LogFile))
		os.Exit(1)
	}
}

func runTests(conf gotop.Config) int {
	fmt.Printf("PASS")
	return 0
}