package main

import (
	"bufio"
	"fmt"
	"math/rand"
	"os"
	"strings"
)

func readFile(filename string) []string {
	f, _ := os.Open(filename)
	defer f.Close()

	scanner := bufio.NewScanner(f)
	scanner.Split(bufio.ScanWords)
	var words []string
	for scanner.Scan() {
		words = append(words, strings.ToLower(scanner.Text()))
	}
	return words
}

func makePairs(words []string) [][]string {
	var pairs [][]string
	for i := 0; i < len(words)-1; i++ {
		pairs = append(pairs, words[i:i+2])
	}
	return pairs
}

func buildCFD(pairs [][]string) map[string]map[string]int {

	CFD := make(map[string]map[string]int)
	for i := range pairs {
		word1 := pairs[i][0]
		word2 := pairs[i][1]

		// a map returns two values: the 'value' in the key-value pair and a bool
		// representing whether the key exists
		_, wordexists := CFD[word1]

		if wordexists {
			_, fd_exists := CFD[word1][word2]

			if fd_exists {
				CFD[word1][word2]++
			} else {
				CFD[word1][word2] = 1
			}

		} else {
			CFD[word1] = map[string]int{word2: 1}
		}
	}
	return CFD

}

func pickRandWord(probabilitySpread []string) string {
	randomIndex := rand.Intn(len(probabilitySpread))
	return probabilitySpread[randomIndex]
}

func generateText(CFD map[string]map[string]int) []string {
	text := make([]string, 10)
	word := "the"
	for i := range text {
		wordCFD := CFD[word]
		var probabilitySpread []string
		for word2, freq := range wordCFD {
			for j := 0; j <= freq; j++ {
				probabilitySpread = append(probabilitySpread, word2)
			}
		}
		randword := pickRandWord(probabilitySpread)

		text[i] = word
		word = randword
	}
	return text

}

func main() {
	words := readFile("./deluze.txt")
	pairs := makePairs(words)
	CFD := buildCFD(pairs)
	text := generateText(CFD)
	fmt.Print(strings.Join(text, " "))
	fmt.Print("\n")
}