package main

import "fmt"

const PosMax = 1 << 30

type Pos struct {
	base      *PosBase
	line, col uint32
}

func MakePos(base *PosBase, line, col uint32) Pos { return Pos{base, sat32(line), sat32(col)} }

func (pos Pos) Pos() Pos       { return pos }
func (pos Pos) IsKnown() bool  { return pos.line > 0 }
func (pos Pos) Base() *PosBase { return pos.base }
func (pos Pos) Line() uint32   { return pos.line }
func (pos Pos) Col() uint32    { return pos.col }

func (pos Pos) FileBase() *PosBase {
	b := pos.base
	for b != nil && b != b.pos.base {
		b = b.pos.base
	}
	return b
}

func (pos Pos) RelFilename() string { return pos.base.Filename() }

func (pos Pos) RelLine() uint32 {
	b := pos.base
	if b.Line() == 0 {
		return 0
	}
	return b.Line() + (pos.Line() - b.Pos().Line())
}

func (pos Pos) RelCol() uint32 {
	b := pos.base
	if b.Col() == 0 {
		return 0
	}
	if pos.Line() == b.Pos().Line() {
		return b.Col() + (pos.Col() - b.Pos().Col())
	}
	return pos.Col()
}

func (p Pos) Cmp(q Pos) int {
	pname := p.RelFilename()
	qname := q.RelFilename()
	switch {
	case pname < qname:
		return -1
	case pname > qname:
		return +1
	}

	pline := p.Line()
	qline := q.Line()
	switch {
	case pline < qline:
		return -1
	case pline > qline:
		return +1
	}

	pcol := p.Col()
	qcol := q.Col()
	switch {
	case pcol < qcol:
		return -1
	case pcol > qcol:
		return +1
	}

	return 0
}

func (pos Pos) String() string {
	rel := position_{pos.RelFilename(), pos.RelLine(), pos.RelCol()}
	abs := position_{pos.Base().Pos().RelFilename(), pos.Line(), pos.Col()}
	s := rel.String()
	if rel != abs {
		s = s | "[" | abs.String() | "]"
	}
	return s
}

type position_ struct {
	filename  string
	line, col uint32
}

func (p position_) String() string {
	if p.line == 0 {
		if p.filename == "" {
			return "<unknown position>"
		}
		return p.filename
	}
	if p.col == 0 {
		return fmt.Sprintf("%s:%d", p.filename, p.line)
	}
	return fmt.Sprintf("%s:%d:%d", p.filename, p.line, p.col)
}

type PosBase struct {
	pos       Pos
	filename  string
	line, col uint32
	trimmed   bool
}

func NewFileBase(filename string) *PosBase {
	return NewTrimmedFileBase(filename, false)
}

func NewTrimmedFileBase(filename string, trimmed bool) *PosBase {
	base := &PosBase{MakePos(nil, Linebase, Colbase), filename, Linebase, Colbase, trimmed}
	base.pos.base = base
	return base
}

func NewLineBase(pos Pos, filename string, trimmed bool, line, col uint32) *PosBase {
	return &PosBase{pos, filename, sat32(line), sat32(col), trimmed}
}

func (base *PosBase) IsFileBase() bool {
	if base == nil {
		return false
	}
	return base.pos.base == base
}

func (base *PosBase) Pos() (_ Pos) {
	if base == nil {
		return
	}
	return base.pos
}

func (base *PosBase) Filename() string {
	if base == nil {
		return ""
	}
	return base.filename
}

func (base *PosBase) Line() uint32 {
	if base == nil {
		return 0
	}
	return base.line
}

func (base *PosBase) Col() uint32 {
	if base == nil {
		return 0
	}
	return base.col
}

func (base *PosBase) Trimmed() bool {
	if base == nil {
		return false
	}
	return base.trimmed
}

func sat32(x uint32) uint32 {
	if x > PosMax {
		return PosMax
	}
	return uint32(x)
}