package main

import (
	"bufio"
	"fmt"
	"io"
	"strings"
)

import (
	"mailq-inspector/mailq"
)

type shellState struct {
	SortConfig mailq.QSortConfig
	QuitShell  bool
	Queue      mailq.MailQ
}

func initialShellState() shellState {
	var state shellState = shellState{}
	state.QuitShell = false
	state.SortConfig = defaultSortConfig()
	state = refreshQueue(state)
	return state
}

func refreshQueue(state shellState) shellState {
	queue, err := fetchQueue()
	if err != nil {
		fmt.Printf("Error fetching queue: '%s'\n", err.Error())
	}
	state.Queue = queue
	return state
}

func updateSortConfig(fields []string, state shellState) shellState {
	sortConfig := mailq.NewSortConfig()
	var err error
	for _, field := range fields[1:] {
		split := strings.Split(field, ":")
		sortConfig, err = sortConfig.By(split[0], split[1])
		if err != nil {
			fmt.Printf("Error applying sort config: '%s'\n", err.Error())
		}
	}
	state.SortConfig = sortConfig
	return state
}

func displayMessageDetails(fields []string, writer io.Writer, state shellState) {
	if len(fields) < 2 {
		fmt.Fprintln(writer, "Please state the Id of the message to inspect!")
		return
	}
	messageId := fields[1]
	message, err := state.Queue.GetMessageById(messageId)
	if err != nil {
		fmt.Fprintf(writer, "Could not inspect message with id '%s': '%s'\n", messageId, err.Error())
	} else {
		fmt.Fprintf(writer, "%s\n", message.DetailedString())
	}
}

func interactiveShell(reader io.Reader, writer io.Writer) {
	var state shellState = initialShellState()
	printHelp(writer)
	scanner := bufio.NewScanner(reader)
	for {
		fmt.Fprint(writer, "> ")
		if !scanner.Scan() {
			fmt.Println()
			break
		}
		text := strings.Trim(scanner.Text(), " ")
		textFields := strings.Fields(text)
		if len(textFields) == 0 {
			continue
		}
		cmd := textFields[0]
		switch cmd {
		case "help", "?":
			printHelp(writer)
		case "exit":
			state.QuitShell = true
		case "inspect":
			displayMessageDetails(textFields, writer, state)
		case "sort":
			state = updateSortConfig(textFields, state)
		case "show":
			state.Queue.Sort(state.SortConfig)
			displayQueue(state.Queue)
		case "summary":
			state.Queue.WriteSummary(writer)
		case "reload":
			state = refreshQueue(state)
			fmt.Fprintln(writer, "Queue data reloaded")
			state.Queue.WriteSummary(writer)
		default:
			fmt.Fprintf(writer, "Unknown command '%s'\n", cmd)
			fmt.Fprintln(writer, "Use 'help' to display help command")
		}
		if state.QuitShell == true {
			break
		}
	}
}

func printHelp(writer io.Writer) {
	fmt.Fprintln(writer, "Available commands:")
	fmt.Fprintln(writer, "help\tdisplay this output")
	fmt.Fprintln(writer, "exit\tquit this program")
	fmt.Fprintln(writer, "reload\treload mailq")
	fmt.Fprintln(writer, "sort\tdefine how to sort mailq before showing")
	fmt.Fprintln(writer, "show\tshow mailq")
	fmt.Fprintln(writer, "summary\tshow mailq summary")
	fmt.Fprintln(writer, "")
}