package main

import (
	"fmt"
	"strings"
)

//------------------------------------------------\\
// + + +             T Y P E S               + + + \\
//--------------------------------------------------\\

type Pages struct {
	Position int
	Length int
	History [20]Page
}


//------------------------------------------------\\
// + + +           R E C E I V E R S         + + + \\
//--------------------------------------------------\\

func (p *Pages) NavigateHistory(qty int) error {
	newPosition := p.Position + qty
	if newPosition < 0 {
		return fmt.Errorf("You are already at the beginning of history")
	} else if newPosition > p.Length - 1 {
		return fmt.Errorf("Your way is blocked by void, there is nothing forward")
	}

	p.Position = newPosition
	return nil
}

func (p *Pages) Add(pg Page) {
	if p.Position == p.Length - 1 && p.Length < len(p.History) {
		p.History[p.Length] = pg
		p.Length++
		p.Position++
	} else if p.Position == p.Length - 1 && p.Length == 20 {
		for x := 1; x < len(p.History); x++ {
			p.History[x-1] = p.History[x]
		}
		p.History[len(p.History)-1] = pg
	} else {
		p.Position += 1
		p.Length = p.Position + 1
		p.History[p.Position] = pg
	}
}

func (p *Pages) Render(termHeight int) []string {
	if p.Length < 1 {
		msg := "Welcome to Bombadillo,\nif this is your first time here\ntype:\n\n:help\n(and then press enter)"
		return strings.Split(msg, "\n")
	}
	beg, end := p.History[p.Position].ScrollPositionRange(termHeight)
	return p.History[p.Position].WrappedContent[beg:end]
}

//------------------------------------------------\\
// + + +          F U N C T I O N S          + + + \\
//--------------------------------------------------\\

func MakePages() Pages {
	return Pages{-1, 0, [20]Page{}}
}