package pretty

import (
	"sort"
)

// Options is Pretty options
type Options struct {
	// Width is an max column width for single line arrays
	// Default is 80
	Width int
	// Prefix is a prefix for all lines
	// Default is an empty string
	Prefix string
	// Indent is the nested indentation
	// Default is two spaces
	Indent string
	// SortKeys will sort the keys alphabetically
	// Default is false
	SortKeys bool
}

// DefaultOptions is the default options for pretty formats.
var DefaultOptions = &Options{Width: 80, Prefix: "", Indent: "  ", SortKeys: false}

// Pretty converts the input json into a more human readable format where each
// element is on it's own line with clear indentation.
func Pretty(json []byte) []byte { return PrettyOptions(json, nil) }

// PrettyOptions is like Pretty but with customized options.
func PrettyOptions(json []byte, opts *Options) []byte {
	if opts == nil {
		opts = DefaultOptions
	}
	buf := make([]byte, 0, len(json))
	if len(opts.Prefix) != 0 {
		buf = append(buf, opts.Prefix...)
	}
	buf, _, _, _ = appendPrettyAny(buf, json, 0, true,
		opts.Width, opts.Prefix, opts.Indent, opts.SortKeys,
		0, 0, -1)
	if len(buf) > 0 {
		buf = append(buf, '\n')
	}
	return buf
}

// Ugly removes insignificant space characters from the input json byte slice
// and returns the compacted result.
func Ugly(json []byte) []byte {
	buf := make([]byte, 0, len(json))
	return ugly(buf, json)
}

// UglyInPlace removes insignificant space characters from the input json
// byte slice and returns the compacted result. This method reuses the
// input json buffer to avoid allocations. Do not use the original bytes
// slice upon return.
func UglyInPlace(json []byte) []byte { return ugly(json, json) }

func ugly(dst, src []byte) []byte {
	dst = dst[:0]
	for i := 0; i < len(src); i++ {
		if src[i] > ' ' {
			dst = append(dst, src[i])
			if src[i] == '"' {
				for i = i + 1; i < len(src); i++ {
					dst = append(dst, src[i])
					if src[i] == '"' {
						j := i - 1
						for ; ; j-- {
							if src[j] != '\\' {
								break
							}
						}
						if (j-i)%2 != 0 {
							break
						}
					}
				}
			}
		}
	}
	return dst
}

func appendPrettyAny(buf, json []byte, i int, pretty bool, width int, prefix, indent string, sortkeys bool, tabs, nl, max int) ([]byte, int, int, bool) {
	for ; i < len(json); i++ {
		if json[i] <= ' ' {
			continue
		}
		if json[i] == '"' {
			return appendPrettyString(buf, json, i, nl)
		}
		if (json[i] >= '0' && json[i] <= '9') || json[i] == '-' {
			return appendPrettyNumber(buf, json, i, nl)
		}
		if json[i] == '{' {
			return appendPrettyObject(buf, json, i, '{', '}', pretty, width, prefix, indent, sortkeys, tabs, nl, max)
		}
		if json[i] == '[' {
			return appendPrettyObject(buf, json, i, '[', ']', pretty, width, prefix, indent, sortkeys, tabs, nl, max)
		}
		switch json[i] {
		case 't':
			return append(buf, 't', 'r', 'u', 'e'), i + 4, nl, true
		case 'f':
			return append(buf, 'f', 'a', 'l', 's', 'e'), i + 5, nl, true
		case 'n':
			return append(buf, 'n', 'u', 'l', 'l'), i + 4, nl, true
		}
	}
	return buf, i, nl, true
}

type pair struct {
	kstart, kend int
	vstart, vend int
}

type byKeyVal struct {
	sorted bool
	json   []byte
	pairs  []pair
}

func (arr *byKeyVal) Len() int {
	return len(arr.pairs)
}
func (arr *byKeyVal) Less(i, j int) bool {
	key1 := arr.json[arr.pairs[i].kstart+1 : arr.pairs[i].kend-1]
	key2 := arr.json[arr.pairs[j].kstart+1 : arr.pairs[j].kend-1]
	if string(key1) < string(key2) {
		return true
	}
	if string(key1) > string(key2) {
		return false
	}
	return arr.pairs[i].vstart < arr.pairs[j].vstart
}
func (arr *byKeyVal) Swap(i, j int) {
	arr.pairs[i], arr.pairs[j] = arr.pairs[j], arr.pairs[i]
	arr.sorted = true
}

func appendPrettyObject(buf, json []byte, i int, open, close byte, pretty bool, width int, prefix, indent string, sortkeys bool, tabs, nl, max int) ([]byte, int, int, bool) {
	var ok bool
	if width > 0 {
		if pretty && open == '[' && max == -1 {
			// here we try to create a single line array
			max := width - (len(buf) - nl)
			if max > 3 {
				s1, s2 := len(buf), i
				buf, i, _, ok = appendPrettyObject(buf, json, i, '[', ']', false, width, prefix, "", sortkeys, 0, 0, max)
				if ok && len(buf)-s1 <= max {
					return buf, i, nl, true
				}
				buf = buf[:s1]
				i = s2
			}
		} else if max != -1 && open == '{' {
			return buf, i, nl, false
		}
	}
	buf = append(buf, open)
	i++
	var pairs []pair
	if open == '{' && sortkeys {
		pairs = make([]pair, 0, 8)
	}
	var n int
	for ; i < len(json); i++ {
		if json[i] <= ' ' {
			continue
		}
		if json[i] == close {
			if pretty {
				if open == '{' && sortkeys {
					buf = sortPairs(json, buf, pairs)
				}
				if n > 0 {
					nl = len(buf)
					if buf[nl-1] == ' ' {
						buf[nl-1] = '\n'
					} else {
						buf = append(buf, '\n')
					}
				}
				if buf[len(buf)-1] != open {
					buf = appendTabs(buf, prefix, indent, tabs)
				}
			}
			buf = append(buf, close)
			return buf, i + 1, nl, open != '{'
		}
		if open == '[' || json[i] == '"' {
			if n > 0 {
				buf = append(buf, ',')
				if width != -1 && open == '[' {
					buf = append(buf, ' ')
				}
			}
			var p pair
			if pretty {
				nl = len(buf)
				if buf[nl-1] == ' ' {
					buf[nl-1] = '\n'
				} else {
					buf = append(buf, '\n')
				}
				if open == '{' && sortkeys {
					p.kstart = i
					p.vstart = len(buf)
				}
				buf = appendTabs(buf, prefix, indent, tabs+1)
			}
			if open == '{' {
				buf, i, nl, _ = appendPrettyString(buf, json, i, nl)
				if sortkeys {
					p.kend = i
				}
				buf = append(buf, ':')
				if pretty {
					buf = append(buf, ' ')
				}
			}
			buf, i, nl, ok = appendPrettyAny(buf, json, i, pretty, width, prefix, indent, sortkeys, tabs+1, nl, max)
			if max != -1 && !ok {
				return buf, i, nl, false
			}
			if pretty && open == '{' && sortkeys {
				p.vend = len(buf)
				if p.kstart > p.kend || p.vstart > p.vend {
					// bad data. disable sorting
					sortkeys = false
				} else {
					pairs = append(pairs, p)
				}
			}
			i--
			n++
		}
	}
	return buf, i, nl, open != '{'
}
func sortPairs(json, buf []byte, pairs []pair) []byte {
	if len(pairs) == 0 {
		return buf
	}
	vstart := pairs[0].vstart
	vend := pairs[len(pairs)-1].vend
	arr := byKeyVal{false, json, pairs}
	sort.Stable(&arr)
	if !arr.sorted {
		return buf
	}
	nbuf := make([]byte, 0, vend-vstart)
	for i, p := range pairs {
		nbuf = append(nbuf, buf[p.vstart:p.vend]...)
		if i < len(pairs)-1 {
			nbuf = append(nbuf, ',')
			nbuf = append(nbuf, '\n')
		}
	}
	return append(buf[:vstart], nbuf...)
}

func appendPrettyString(buf, json []byte, i, nl int) ([]byte, int, int, bool) {
	s := i
	i++
	for ; i < len(json); i++ {
		if json[i] == '"' {
			var sc int
			for j := i - 1; j > s; j-- {
				if json[j] == '\\' {
					sc++
				} else {
					break
				}
			}
			if sc%2 == 1 {
				continue
			}
			i++
			break
		}
	}
	return append(buf, json[s:i]...), i, nl, true
}

func appendPrettyNumber(buf, json []byte, i, nl int) ([]byte, int, int, bool) {
	s := i
	i++
	for ; i < len(json); i++ {
		if json[i] <= ' ' || json[i] == ',' || json[i] == ':' || json[i] == ']' || json[i] == '}' {
			break
		}
	}
	return append(buf, json[s:i]...), i, nl, true
}

func appendTabs(buf []byte, prefix, indent string, tabs int) []byte {
	if len(prefix) != 0 {
		buf = append(buf, prefix...)
	}
	if len(indent) == 2 && indent[0] == ' ' && indent[1] == ' ' {
		for i := 0; i < tabs; i++ {
			buf = append(buf, ' ', ' ')
		}
	} else {
		for i := 0; i < tabs; i++ {
			buf = append(buf, indent...)
		}
	}
	return buf
}

// Style is the color style
type Style struct {
	Key, String, Number [2]string
	True, False, Null   [2]string
	Escape              [2]string
	Append              func(dst []byte, c byte) []byte
}

func hexp(p byte) byte {
	switch {
	case p < 10:
		return p + '0'
	default:
		return (p - 10) + 'a'
	}
}

// TerminalStyle is for terminals
var TerminalStyle *Style

func init() {
	TerminalStyle = &Style{
		Key:    [2]string{"\x1B[94m", "\x1B[0m"},
		String: [2]string{"\x1B[92m", "\x1B[0m"},
		Number: [2]string{"\x1B[93m", "\x1B[0m"},
		True:   [2]string{"\x1B[96m", "\x1B[0m"},
		False:  [2]string{"\x1B[96m", "\x1B[0m"},
		Null:   [2]string{"\x1B[91m", "\x1B[0m"},
		Escape: [2]string{"\x1B[35m", "\x1B[0m"},
		Append: func(dst []byte, c byte) []byte {
			if c < ' ' && (c != '\r' && c != '\n' && c != '\t' && c != '\v') {
				dst = append(dst, "\\u00"...)
				dst = append(dst, hexp((c>>4)&0xF))
				return append(dst, hexp((c)&0xF))
			}
			return append(dst, c)
		},
	}
}

// Color will colorize the json. The style parma is used for customizing
// the colors. Passing nil to the style param will use the default
// TerminalStyle.
func Color(src []byte, style *Style) []byte {
	if style == nil {
		style = TerminalStyle
	}
	apnd := style.Append
	if apnd == nil {
		apnd = func(dst []byte, c byte) []byte {
			return append(dst, c)
		}
	}
	type stackt struct {
		kind byte
		key  bool
	}
	var dst []byte
	var stack []stackt
	for i := 0; i < len(src); i++ {
		if src[i] == '"' {
			key := len(stack) > 0 && stack[len(stack)-1].key
			if key {
				dst = append(dst, style.Key[0]...)
			} else {
				dst = append(dst, style.String[0]...)
			}
			dst = apnd(dst, '"')
			esc := false
			uesc := 0
			for i = i + 1; i < len(src); i++ {
				if src[i] == '\\' {
					if key {
						dst = append(dst, style.Key[1]...)
					} else {
						dst = append(dst, style.String[1]...)
					}
					dst = append(dst, style.Escape[0]...)
					dst = apnd(dst, src[i])
					esc = true
					if i+1 < len(src) && src[i+1] == 'u' {
						uesc = 5
					} else {
						uesc = 1
					}
				} else if esc {
					dst = apnd(dst, src[i])
					if uesc == 1 {
						esc = false
						dst = append(dst, style.Escape[1]...)
						if key {
							dst = append(dst, style.Key[0]...)
						} else {
							dst = append(dst, style.String[0]...)
						}
					} else {
						uesc--
					}
				} else {
					dst = apnd(dst, src[i])
				}
				if src[i] == '"' {
					j := i - 1
					for ; ; j-- {
						if src[j] != '\\' {
							break
						}
					}
					if (j-i)%2 != 0 {
						break
					}
				}
			}
			if esc {
				dst = append(dst, style.Escape[1]...)
			} else if key {
				dst = append(dst, style.Key[1]...)
			} else {
				dst = append(dst, style.String[1]...)
			}
		} else if src[i] == '{' || src[i] == '[' {
			stack = append(stack, stackt{src[i], src[i] == '{'})
			dst = apnd(dst, src[i])
		} else if (src[i] == '}' || src[i] == ']') && len(stack) > 0 {
			stack = stack[:len(stack)-1]
			dst = apnd(dst, src[i])
		} else if (src[i] == ':' || src[i] == ',') && len(stack) > 0 && stack[len(stack)-1].kind == '{' {
			stack[len(stack)-1].key = !stack[len(stack)-1].key
			dst = apnd(dst, src[i])
		} else {
			var kind byte
			if (src[i] >= '0' && src[i] <= '9') || src[i] == '-' {
				kind = '0'
				dst = append(dst, style.Number[0]...)
			} else if src[i] == 't' {
				kind = 't'
				dst = append(dst, style.True[0]...)
			} else if src[i] == 'f' {
				kind = 'f'
				dst = append(dst, style.False[0]...)
			} else if src[i] == 'n' {
				kind = 'n'
				dst = append(dst, style.Null[0]...)
			} else {
				dst = apnd(dst, src[i])
			}
			if kind != 0 {
				for ; i < len(src); i++ {
					if src[i] <= ' ' || src[i] == ',' || src[i] == ':' || src[i] == ']' || src[i] == '}' {
						i--
						break
					}
					dst = apnd(dst, src[i])
				}
				if kind == '0' {
					dst = append(dst, style.Number[1]...)
				} else if kind == 't' {
					dst = append(dst, style.True[1]...)
				} else if kind == 'f' {
					dst = append(dst, style.False[1]...)
				} else if kind == 'n' {
					dst = append(dst, style.Null[1]...)
				}
			}
		}
	}
	return dst
}

// Spec strips out comments and trailing commas and convert the input to a
// valid JSON per the official spec: https://tools.ietf.org/html/rfc8259
//
// The resulting JSON will always be the same length as the input and it will
// include all of the same line breaks at matching offsets. This is to ensure
// the result can be later processed by a external parser and that that
// parser will report messages or errors with the correct offsets.
func Spec(src []byte) []byte {
	return spec(src, nil)
}

// SpecInPlace is the same as Spec, but this method reuses the input json
// buffer to avoid allocations. Do not use the original bytes slice upon return.
func SpecInPlace(src []byte) []byte {
	return spec(src, src)
}

func spec(src, dst []byte) []byte {
	dst = dst[:0]
	for i := 0; i < len(src); i++ {
		if src[i] == '/' {
			if i < len(src)-1 {
				if src[i+1] == '/' {
					dst = append(dst, ' ', ' ')
					i += 2
					for ; i < len(src); i++ {
						if src[i] == '\n' {
							dst = append(dst, '\n')
							break
						} else if src[i] == '\t' || src[i] == '\r' {
							dst = append(dst, src[i])
						} else {
							dst = append(dst, ' ')
						}
					}
					continue
				}
				if src[i+1] == '*' {
					dst = append(dst, ' ', ' ')
					i += 2
					for ; i < len(src)-1; i++ {
						if src[i] == '*' && src[i+1] == '/' {
							dst = append(dst, ' ', ' ')
							i++
							break
						} else if src[i] == '\n' || src[i] == '\t' ||
							src[i] == '\r' {
							dst = append(dst, src[i])
						} else {
							dst = append(dst, ' ')
						}
					}
					continue
				}
			}
		}
		dst = append(dst, src[i])
		if src[i] == '"' {
			for i = i + 1; i < len(src); i++ {
				dst = append(dst, src[i])
				if src[i] == '"' {
					j := i - 1
					for ; ; j-- {
						if src[j] != '\\' {
							break
						}
					}
					if (j-i)%2 != 0 {
						break
					}
				}
			}
		} else if src[i] == '}' || src[i] == ']' {
			for j := len(dst) - 2; j >= 0; j-- {
				if dst[j] <= ' ' {
					continue
				}
				if dst[j] == ',' {
					dst[j] = ' '
				}
				break
			}
		}
	}
	return dst
}
