package bibtex

import (
	"bytes"
	"log"
	"strings"
	"unicode"
)

const sepChars = "-~"

var lcommands map[string]bool = map[string]bool{
	"aa": true, "oe": true, "l": true, "ae": true,
	"o": true, "ss": true, "i": true, "j": true,
}

var ucommands map[string]bool = map[string]bool{
	"AA": true, "L": true, "OE": true, "AE": true, "O": true,
}

type Token struct {
	Sep  rune // the separator preceding the token
	Text string
}

type NamePart []Token

// a proto name before the parts have been separated in f,v,l,f
type name []NamePart

// abbreviate a string. return the first letter or special character
func _abbrv(s string) string {
	reader := newReader(s)
	var buf bytes.Buffer
	for c := reader.readRune(); c != eof; c = reader.readRune() {
		switch {
		case c == '{':
			c = reader.readRune()
			if c == '\\' {
				buf.WriteString("{\\")
				buf.WriteString(reader.readBraces())
				return buf.String()
			} else {
				reader.UnreadRune()
			}
		case unicode.IsLetter(c):
			buf.WriteRune(c)
			return buf.String()
		}
	}
	return buf.String()
}

func printSep(buf *bytes.Buffer, sep rune, last bool) {
	switch {
	case sep == '-', sep == '~':
		buf.WriteRune(sep)
	case last || length(buf.String()) <= 2:
		buf.WriteRune('~')
	default:
		buf.WriteRune(' ')
	}
}

// Format returns a string representation of NamePart p.
// If abbrv the token will be abbreviated. If def is true, the default
// inter-token will be used: this is either space or ~ depending on the length
// of the token. If def is false sep is used as the inter-token separator.
func (p NamePart) Format(abbrv bool, sep string, def bool) string {
	var buf bytes.Buffer
	for i, t := range p {
		if i > 0 {
			if abbrv {
				buf.WriteRune('.')
			}
			if def {
				printSep(&buf, t.Sep, i == len(p)-1)
			} else {
				buf.WriteString(sep)
			}
		}
		if abbrv {
			buf.WriteString(_abbrv(t.Text))
		} else {
			buf.WriteString(t.Text)
		}
	}
	return buf.String()
}

func addNonEmptyToken(b *bytes.Buffer, t *Token, part *NamePart, c rune) {
	if b.Len() > 0 {
		t.Text = b.String()
		b.Reset()
		*part = append(*part, *t)
		*t = Token{Sep: c}
	}
}

func addNonEmptyPart(part *NamePart, name *name, t *Token, c rune) {
	if len(*part) > 0 || len(*name) == 0 {
		*name = append(*name, *part)
	}
	*part = nil
	*t = Token{Sep: c}
}

// tokenize a string and return a list of proto names, the parts of the proto
// name are the result of splitting on commas, but further splitting is done
// later
func splitNames(s string) (names []name) {
	if len(s) == 0 {
		return nil
	}
	var name name                 // current name
	var part NamePart             // current name Part
	Token := &Token{Sep: rune(0)} // current token
	bracelevel := 0
	space := false // was the last non-special character a WS?
	var buf bytes.Buffer
	for _, c := range s {
		switch {
		case c == '{':
			buf.WriteRune(c)
			bracelevel += 1
		case c == '}':
			buf.WriteRune(c)
			bracelevel -= 1
		case unicode.IsSpace(c) && bracelevel == 0:
			if space && strings.ToLower(buf.String()) == "and" {
				buf.Reset()
				addNonEmptyPart(&part, &name, Token, c)
				names = append(names, name)
				name = nil
			}
			addNonEmptyToken(&buf, Token, &part, c)
			space = true
		case bracelevel == 0 && strings.ContainsRune(sepChars, c):
			space = false
			addNonEmptyToken(&buf, Token, &part, c)
		case bracelevel == 0 && c == ',':
			space = false
			addNonEmptyToken(&buf, Token, &part, c)
			// a name cannot have more than 3 proto parts, hence  a comma
			// counts as a separation between parts only the first two times,
			// i.e. when len(name) == 0 or len(name) == 1
			if len(name) <= 1 {
				addNonEmptyPart(&part, &name, Token, c)
			}
		default:
			buf.WriteRune(c)
		}
	}
	addNonEmptyToken(&buf, Token, &part, ',')
	addNonEmptyPart(&part, &name, Token, ',')
	names = append(names, name)
	return
}

type Name struct {
	First NamePart
	Von   NamePart
	Last  NamePart
	Jr    NamePart
}

func (n Name) getPart(c rune) (p NamePart) {
	switch c {
	case 'f':
		p = n.First
	case 'v':
		p = n.Von
	case 'l':
		p = n.Last
	case 'j':
		p = n.Jr
	}
	return
}

// here the format string f is assumed to only contain one part
func (n Name) formatPart(f string) string {
	f = f[1 : len(f)-1]
	r := newReader(f)
	var buf bytes.Buffer
	abbrv := true
	found := false
	def := true
	sep := ""
	for c := r.readRune(); c != eof; c = r.readRune() {
		switch {
		case strings.ContainsRune("fvljFVLJ", c) && !found:
			found = true
			typ := unicode.ToLower(c)
			if d := r.readRune(); unicode.ToLower(d) == typ {
				abbrv = false
			} else {
				r.UnreadRune()
			}
			if d := r.readRune(); d == '{' {
				def = false
				sep = "{" + r.readBraces()
				sep = sep[1 : len(sep)-1]
			} else {
				r.UnreadRune()
			}
			part := n.getPart(typ)
			if len(part) == 0 {
				return ""
			}
			s := part.Format(abbrv, sep, def)
			buf.WriteString(s)
		case unicode.IsLetter(c):
			log.Printf("Non valid char")
		default:
			buf.WriteRune(c)
		}
	}
	return dtie(buf.String())
}

// handles discretionary ties
func dtie(s string) string {
	if len(s) >= 2 && s[len(s)-1] == '~' && s[len(s)-2] != '~' {
		s = s[:len(s)-1]
		if length(s) <= 2 {
			s += "~"
		} else {
			s += " "
		}
	}
	return s
}

// Format formats the name n according to the format string s.
func (n Name) Format(s string) string {
	r := newReader(s)
	var buf bytes.Buffer
	for c := r.readRune(); c != eof; c = r.readRune() {
		switch {
		case c == '{':
			fmt := "{" + r.readBraces()
			buf.WriteString(n.formatPart(fmt))
		case c == '}':
			log.Printf("Unbalanced braced in format string %s", s)
		default:
			buf.WriteRune(c)
		}
	}
	return buf.String()
}

// the von part starts at the first non last lower-case taken
func findVon(part NamePart) int {
	for i, t := range part {
		if isLower(t.Text) && i < len(part)-1 {
			return i
		}
	}
	return -1
}

// reading tokens from the penultimate token, the boundary between von and last
// is after the first lower token
func splitVonLast(part NamePart) (NamePart, NamePart) {
	var i int
	if len(part) < 2 {
		return part[:0], part[:]
	}
	for i = len(part) - 2; i >= 0; i-- {
		if isLower(part[i].Text) {
			i += 1
			break
		}
	}
	if i == -1 {
		return part[:0], part[:]
	} else {
		return part[:i], part[i:]
	}
}

// only when there is no von part and no comma
// reading tokens from the last token, tokens are added to the last name if
// they are connected to the following token by a hyphen
func splitFirstLast(part NamePart) (NamePart, NamePart) {
	var i int
	if len(part) == 0 {
		return part[:0], part[:]
	}
	for i = len(part) - 1; i >= 0; i-- {
		if part[i].Sep != '-' {
			break
		}
	}
	if i == -1 {
		return part[:0], part[:]
	} else {
		return part[:i], part[i:]
	}
}

// SplitNames parses the string s and returns a list of names.
func SplitNames(s string) (res []Name) {
	names := splitNames(s)
	var first, von, last, vonlast, jr NamePart
	for _, name := range names {
		first, von, last, vonlast, jr = nil, nil, nil, nil, nil
		if len(name) == 1 {
			i := findVon(name[0])
			if i >= 0 {
				first = name[0][:i]
				vonlast = name[0][i:]
				von, last = splitVonLast(vonlast)
			} else {
				first, last = splitFirstLast(name[0])
			}
		} else if len(name) == 2 {
			vonlast = name[0]
			von, last = splitVonLast(vonlast)
			first = name[1]
		} else if len(name) == 3 {
			vonlast = name[0]
			von, last = splitVonLast(vonlast)
			first = name[2]
			jr = name[1]
		}
		res = append(res, Name{first, von, last, jr})
	}
	return
}