package solver

import (
	"flag"
	"fmt"
	"log"
	"os"
	"runtime"
)

func (solver *Solver) parseFlags() {

	// Define variables
	var row1 string
	var row2 string
	var row3 string
	var row4 string
	var row5 string
	var row6 string
	var row7 string
	var row8 string
	var row9 string
	var split int
	var part int

	// Define parameters
	flag.StringVar(&row1, "row1", "000000000", "1st row of the sudoku puzzle.")
	flag.StringVar(&row2, "row2", "000000000", "2nd row of the sudoku puzzle.")
	flag.StringVar(&row3, "row3", "000000000", "4rd row of the sudoku puzzle.")
	flag.StringVar(&row4, "row4", "000000000", "4th row of the sudoku puzzle.")
	flag.StringVar(&row5, "row5", "000000000", "5th row of the sudoku puzzle.")
	flag.StringVar(&row6, "row6", "000000000", "6th row of the sudoku puzzle.")
	flag.StringVar(&row7, "row7", "000000000", "7th row of the sudoku puzzle.")
	flag.StringVar(&row8, "row8", "000000000", "8th row of the sudoku puzzle.")
	flag.StringVar(&row9, "row9", "000000000", "9th row of the sudoku puzzle.")
	flag.IntVar(&solver.numCPUs, "numcpu", runtime.NumCPU(), "Number of CPU cores to assign to this task.")
	flag.IntVar(&split, "split", 1, "Split the tasks in n parts. This depends on the availability of the first row.")
	flag.IntVar(&part, "part", 1, "Process part x in n parts. Cannot be lower than 1, or higher than specified in split.")

	// Parse the flags
	flag.Parse()

	// Process any changes to the CPU usage.
	if solver.numCPUs <= 0 {
		log.Printf("ERROR: Number of CPU cores must be 1 or higher.\n\n")
		solver.printUsage()
		os.Exit(1)
	}

	if solver.numCPUs != runtime.NumCPU() {
		runtime.GOMAXPROCS(solver.numCPUs)
	}

	// Process rows
	if row1 == "000000000" || row2 == "000000000" || row3 == "000000000" || row4 == "000000000" || row5 == "000000000" || row6 == "000000000" || row7 == "000000000" || row8 == "000000000" || row9 == "000000000" {
		log.Printf("ERROR: All parameters must be entered.\n\n")
		solver.printUsage()
		os.Exit(1)
	}

	// Validate the row (never trust user input)
	solver.validateRow("row1", row1)
	solver.validateRow("row2", row2)
	solver.validateRow("row3", row3)
	solver.validateRow("row4", row4)
	solver.validateRow("row5", row5)
	solver.validateRow("row6", row6)
	solver.validateRow("row7", row7)
	solver.validateRow("row8", row8)
	solver.validateRow("row9", row9)

	// Put entries in into the struct
	solver.row1 = row1
	solver.row2 = row2
	solver.row3 = row3
	solver.row4 = row4
	solver.row5 = row5
	solver.row6 = row6
	solver.row7 = row7
	solver.row8 = row8
	solver.row9 = row9

	// Process workload splitting
	// Ensure split and part are 1 or higher
	if split <= 0 || part <= 0 {
		log.Printf("ERROR: '-split' and '-part' need to be 1 or higher.\n")
		solver.printUsage()
		os.Exit(1)
	}

	// Ensure part is between 1 and split
	if part > split {
		log.Printf("ERROR: '-part' cannot be bigger than `-split`.\n")
		solver.printUsage()
		os.Exit(1)
	}

	solver.split = split
	solver.part = part

}

func (solver *Solver) validateRow(name string, row string) {

	var found bool
	var double bool
	count := make(map[rune]int)

	// 1. Make sure the row is 9 in length
	if len(row) != 9 {
		log.Printf("ERROR: Invalid length of %s (%s), must be 9 numbers\n\n", name, row)
		solver.printUsage()
		os.Exit(1)
	}

	// 2. Ensure all digits are numbers
	for _, value := range row {
		found = solver.validChar(value)
	}

	if !found {
		log.Printf("ERROR: Invalid character of %s (%s), must be 9 numbers\n\n", name, row)
		solver.printUsage()
		os.Exit(1)
	}

	// 3. Ensure all digits (except zero) are there only once
	for _, digits := range row {
		count[digits] = count[digits] + 1
	}

	for key, value := range count {
		if value > 1 && key != 48 {
			double = true
		}
	}

	if double {
		log.Printf("ERROR: Double character of %s (%s), numbers between 1 and 9 may only be entered once\n\n", name, row)
		solver.printUsage()
		os.Exit(1)
	}

}

func (solver *Solver) validChar(char rune) (valid bool) {
	decvals := [10]int{48, 49, 50, 51, 52, 53, 54, 55, 56, 57}

	for _, value := range decvals {
		if char == rune(value) {
			valid = true
		}
	}

	return valid
}

func (solver *Solver) printUsage() {
	fmt.Fprintf(flag.CommandLine.Output(), "Usage of %s:\n", os.Args[0])
	fmt.Fprintf(flag.CommandLine.Output(), "\nPut every row of a Sudoku puzzle as paramters.\nUse '0' for what is currently blank in the puzzle you wish to solve.\n\n")
	fmt.Fprintf(flag.CommandLine.Output(), "Example: %s -row1 ... -row2 ... -row3 ... (etc)\n\n", os.Args[0])
	flag.PrintDefaults()
}