package main

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

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

	scanner := bufio.NewScanner(f)
	scanner.Split(bufio.ScanWords)
	words := make([]string, 0)
	for scanner.Scan() {
		words = append(words, strings.ToLower(scanner.Text()))
	}
	return words
}

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

		_, key_exists := CFD[word1]

		if key_exists {
			_, 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, seedWord string) {
	text := make([]string, 10)
	//	text[0] = seedWord
	word1 := seedWord
	for i := range text {
		wordCFD := CFD[word1]
		probabilitySpread := make([]string, 0)
		for word2, freq := range wordCFD {
			for j := 0; j <= freq; j++ {
				probabilitySpread = append(probabilitySpread, word2)
			}
		}
		randword := pickRandWord(probabilitySpread)

		text[i] = word1
		word1 = randword

	}
	fmt.Print(text)

}

func main() {
	words := readText("./text.txt")
	pairs := makePairs(words)
	CFD := buildCFD(pairs)
	generateText(CFD, "the")
}