package textfmt

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"strings"
)

func escapeTeletype(s string) string {
	r := []rune(s)
	for i := range r {
		if r[i] >= 0x00 && r[i] <= 0x1f && r[i] != '\n' && r[i] != '\t' {
			r[i] = 0xb7
		}

		if r[i] >= 0x7f && r[i] <= 0x9f {
			r[i] = 0xb7
		}
	}

	return string(r)
}

func writeLines(w *writer, txt string, indentFirst, indentRest int) {
	lines := strings.Split(txt, "\n")
	for i, l := range lines {
		if i > 0 {
			w.write("\n")
		}

		indent := indentFirst
		if i > 0 {
			indent = indentRest
		}

		w.write(timesn(" ", indent))
		w.write(l)
	}
}

func renderTTYText(w *writer, text Txt) {
	if len(text.cat) > 0 {
		for i, tc := range text.cat {
			if i > 0 {
				w.write(" ")
			}

			renderTTYText(w, tc)
		}

		return
	}

	text.text = singleLine(text.text)
	text.text = escapeTeletype(text.text)
	if text.link != "" {
		if text.text != "" {
			w.write(text.text)
			w.write(" (")
			w.write(text.link)
			w.write(")")
			return
		}

		w.write(text.link)
		return
	}

	w.write(text.text)
}

func ttyTextToString(text Txt) (string, error) {
	var b bytes.Buffer
	w := writer{w: &b}
	renderTTYText(&w, text)
	if w.err != nil {
		return "", w.err
	}

	return b.String(), nil
}

func definitionNames(d []DefinitionItem) ([]string, error) {
	var n []string
	for _, di := range d {
		name, err := ttyTextToString(di.name)
		if err != nil {
			return nil, err
		}

		n = append(n, name)
	}

	return n, nil
}

func renderTTYTitle(w *writer, e Entry) {
	w.write(timesn(" ", e.indentFirst))
	renderTTYText(w, e.text)
}

func renderTTYParagraph(w *writer, e Entry) {
	var txt string
	txt, w.err = ttyTextToString(e.text)
	if e.wrapWidth > 0 {
		txt = wrap(txt, e.wrapWidth, e.indentFirst, e.indentRest)
	}

	writeLines(w, txt, e.indentFirst, e.indentRest)
}

func renderTTYList(w *writer, e Entry) {
	const bullet = "- "
	indentFirst := e.indentFirst
	indentRest := e.indentRest + len(bullet)
	for i, item := range e.items {
		if i > 0 {
			w.write("\n")
		}

		var txt string
		txt, w.err = ttyTextToString(item.text)
		if e.wrapWidth > 0 {
			txt = wrap(txt, e.wrapWidth-len(bullet), indentFirst, indentRest)
		}

		w.write(timesn(" ", indentFirst))
		w.write(bullet)
		writeLines(w, txt, 0, indentRest)
	}
}

func renderTTYNumberedList(w *writer, e Entry) {
	maxDigits := maxDigits(len(e.items))
	indentFirst := e.indentFirst
	indentRest := e.indentRest + maxDigits + 2
	for i, item := range e.items {
		if i > 0 {
			w.write("\n")
		}

		var txt string
		txt, w.err = ttyTextToString(item.text)
		if e.wrapWidth > 0 {
			txt = wrap(txt, e.wrapWidth-maxDigits-2, indentFirst, indentRest)
		}

		w.write(timesn(" ", indentFirst))
		w.write(fmt.Sprintf("%d. ", i))
		writeLines(w, txt, 0, indentRest)
	}
}

func renderTTYDefinitions(w *writer, e Entry) {
	names, err := definitionNames(e.definitions)
	if err != nil {
		w.err = err
		return
	}

	maxLength := maxLength(names)
	indentFirst := e.indentFirst
	indentRest := e.indentRest + maxLength + 4
	for i, def := range e.definitions {
		if i > 0 {
			w.write("\n")
		}

		var value string
		value, w.err = ttyTextToString(def.value)
		if e.wrapWidth > 0 {
			value = wrap(value, e.wrapWidth-maxLength-4, indentFirst, indentRest)
		}

		name := names[i]
		w.write("- ")
		w.write(name)
		w.write(": ")
		writeLines(w, value, 0, indentRest)
	}
}

func renderTTYNumberedDefinitions(w *writer, e Entry) {
	maxDigits := maxDigits(len(e.definitions))
	names, err := definitionNames(e.definitions)
	if err != nil {
		w.err = err
		return
	}

	maxLength := maxLength(names)
	indentFirst := e.indentFirst
	indentRest := e.indentRest + maxLength + maxDigits + 4
	for i, def := range e.definitions {
		if i > 0 {
			w.write("\n")
		}

		var value string
		value, w.err = ttyTextToString(def.value)
		if e.wrapWidth > 0 {
			value = wrap(value, e.wrapWidth-maxLength-4, indentFirst, indentRest)
		}

		name := names[i]
		w.write(fmt.Sprintf("%d. ", i))
		w.write(name)
		w.write(": ")
		writeLines(w, value, 0, indentRest)
	}
}

func ttyCellTexts(rows []TableRow) ([][]string, error) {
	var cellTexts [][]string
	for _, row := range rows {
		var c []string
		for _, cell := range row.cells {
			txt, err := ttyTextToString(cell.text)
			if err != nil {
				return nil, err
			}

			c = append(c, txt)
		}

		cellTexts = append(cellTexts, c)
	}

	return cellTexts, nil
}

func renderTTYTable(w *writer, e Entry) {
	if len(e.rows) == 0 {
		return
	}

	e.rows = normalizeTable(e.rows)
	if len(e.rows[0].cells) == 0 {
		return
	}

	cellTexts, err := ttyCellTexts(e.rows)
	if err != nil {
		w.err = err
	}

	totalSeparatorWidth := (len(cellTexts[0]) - 1) * 3
	if e.wrapWidth > 0 {
		allocatedWidth := e.wrapWidth - e.indentFirst - totalSeparatorWidth
		columnWeights := columnWeights(cellTexts)
		targetColumnWidths := targetColumnWidths(allocatedWidth, columnWeights)
		for i := range cellTexts {
			for j := range cellTexts[i] {
				cellTexts[i][j] = wrap(cellTexts[i][j], targetColumnWidths[j], 0, 0)
			}
		}
	}

	columnWidths := columnWidths(cellTexts)
	totalWidth := totalSeparatorWidth
	for i := range columnWidths {
		totalWidth += columnWidths[i]
	}

	hasHeader := e.rows[0].header
	for i := range cellTexts {
		if i > 0 {
			sep := "-"
			if hasHeader && i == 1 {
				sep = "="
			}

			w.write("\n")
			w.write(timesn(sep, totalWidth))
			w.write("\n")
		}

		for j := range cellTexts[i] {
			if j > 0 {
				w.write(" | ")
			}

			w.write(padRight(cellTexts[i][j], columnWidths[j]))
		}
	}

	if hasHeader && len(cellTexts) == 1 {
		w.write(timesn("=", totalWidth))
	}
}

func renderTTYCode(w *writer, e Entry) {
	var txt string
	txt, w.err = ttyTextToString(e.text)
	writeLines(w, txt, e.indentFirst, e.indentFirst)
}

func renderTTYMultiple(w *writer, s SyntaxItem) {
	s.topLevel = false
	s.multiple = false
	renderTTYSyntaxItem(w, s)
	w.write("...")
}

func renderTTYRequired(w *writer, s SyntaxItem) {
	s.delimited = true
	s.topLevel = false
	s.required = false
	w.write("<")
	renderTTYSyntaxItem(w, s)
	w.write(">")
}

func renderTTYOptional(w *writer, s SyntaxItem) {
	s.delimited = true
	s.topLevel = false
	s.optional = false
	w.write("[")
	renderTTYSyntaxItem(w, s)
	w.write("]")
}

func renderTTYSequence(w *writer, s SyntaxItem) {
	if !s.delimited && !s.topLevel {
		w.write("(")
	}

	for i, item := range s.sequence {
		if i > 0 {
			w.write(" ")
		}

		item.delimited = false
		renderTTYSyntaxItem(w, item)
	}

	if !s.delimited && !s.topLevel {
		w.write(")")
	}
}

func renderTTYChoice(w *writer, s SyntaxItem) {
	if !s.delimited && !s.topLevel {
		w.write("(")
	}

	for i, item := range s.sequence {
		if i > 0 {
			separator := "|"
			if s.topLevel {
				separator = "\n"
			}

			w.write(separator)
		}

		item.delimited = false
		renderTTYSyntaxItem(w, item)
	}

	if !s.delimited && !s.topLevel {
		w.write(")")
	}
}

func renderTTYSymbol(w *writer, s SyntaxItem) {
	w.write(escapeTeletype(s.symbol))
}

func renderTTYSyntaxItem(w *writer, s SyntaxItem) {
	switch {

	// foo...
	case s.multiple:
		renderTTYMultiple(w, s)

	// <foo>
	case s.required:
		renderTTYRequired(w, s)

	// [foo]
	case s.optional:
		renderTTYOptional(w, s)

	// foo bar baz or (foo bar baz)
	case len(s.sequence) > 0:
		renderTTYSequence(w, s)

	// foo|bar|baz or (foo|bar|baz)
	case len(s.choice) > 0:
		renderTTYChoice(w, s)

	// foo
	default:
		renderTTYSymbol(w, s)
	}
}

func renderTTYSyntax(w *writer, e Entry) {
	s := e.syntax
	s.topLevel = true
	renderTTYSyntaxItem(w, s)
}

func renderTeletype(out io.Writer, d Document) error {
	w := writer{w: out}
	for i, e := range d.entries {
		if i > 0 {
			w.write("\n\n")
		}

		switch e.typ {
		case invalid:
			return errors.New("invalid entry")
		case title:
			renderTTYTitle(&w, e)
		case paragraph:
			renderTTYParagraph(&w, e)
		case list:
			renderTTYList(&w, e)
		case numberedList:
			renderTTYNumberedList(&w, e)
		case definitions:
			renderTTYDefinitions(&w, e)
		case numberedDefinitions:
			renderTTYNumberedDefinitions(&w, e)
		case table:
			renderTTYTable(&w, e)
		case code:
			renderTTYCode(&w, e)
		case syntax:
			renderTTYSyntax(&w, e)
		}
	}

	w.write("\n")
	return w.err
}