package main

// What the rules judge a record against and this module does not hold: the reading order's topics
// (02-DECISIONS/README.md) and the glossary's retired words (00-META/glossary.md), read from hq through the
// records module, and the daemons' lines, a copy kept beside this code (daemon-lines, compared with the
// catalogue's own copy by a test).

import (
	_ "embed"
	"fmt"
	"regexp"
	"strings"
	"unicode"
)

//go:embed daemon-lines
var daemonLinesFile string

// Reference is what the rules read besides the records.
type Reference struct {
	Commit string
	// Topics are the reading order's topics.
	Topics []string
	// Retired are the glossary's words retired in hq's prose (no scope, or hq).
	Retired []string
	// Lines are the daemons' lines: a daemon and a command, and whether it is a line only with an argument.
	Lines []DaemonLine
}

// DaemonLine is one daemon's command a person never types.
type DaemonLine struct {
	Daemon, Command string
	WithArgument    bool
}

var (
	topicLine = regexp.MustCompile(`(?m)^\d+\.\s+\*\*([^*]+)\*\*\s+—\s+` + "`" + `topic:\s*([^` + "`" + `]+)` + "`")
	notLine   = regexp.MustCompile(`(?m)^\s*(?:[-*]\s+)?\*Not:\*(.*)$`)
	struck    = regexp.MustCompile(`~~([^~]+)~~(?:\s*\((hq|tools)\))?`)
)

// ReadingOrder is the topics the reading order writes, in order.
func ReadingOrder(readme string) []string {
	var out []string
	for _, m := range topicLine.FindAllStringSubmatch(readme, -1) {
		out = append(out, strings.TrimSpace(m[2]))
	}
	return out
}

// RetiredWords are the glossary's words retired in hq's prose: a struck word on a *Not:* line with no scope or
// the scope hq; "a / b" is two words.
func RetiredWords(glossary string) []string {
	var out []string
	for _, line := range notLine.FindAllStringSubmatch(glossary, -1) {
		for _, m := range struck.FindAllStringSubmatch(line[1], -1) {
			if m[2] == "tools" {
				continue
			}
			for _, w := range strings.Split(m[1], " / ") {
				if w = strings.TrimSpace(w); w != "" {
					out = append(out, w)
				}
			}
		}
	}
	return out
}

// DaemonLines reads the daemons' lines in the catalogue's format: `<daemon> <command>`, ` …` after a command
// that is a line only with an argument after it.
func DaemonLines(file string) []DaemonLine {
	var out []DaemonLine
	for _, line := range strings.Split(file, "\n") {
		line = strings.TrimSpace(line)
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		with := strings.HasSuffix(line, " …")
		line = strings.TrimSuffix(line, " …")
		d, c, ok := strings.Cut(line, " ")
		if ok {
			out = append(out, DaemonLine{Daemon: d, Command: c, WithArgument: with})
		}
	}
	return out
}

// LoadReference reads the reading order and the glossary from hq through the records module.
func LoadReference(records Records) (*Reference, error) {
	commit, err := records.Standing()
	if err != nil {
		return nil, fmt.Errorf("hq cannot be read through the records module (%v)", err)
	}
	readme, _, err := records.Read("02-DECISIONS/README.md")
	if err != nil {
		return nil, fmt.Errorf("the reading order cannot be read (%v)", err)
	}
	glossary, _, err := records.Read("00-META/glossary.md")
	if err != nil {
		return nil, fmt.Errorf("the glossary cannot be read (%v)", err)
	}
	ref := &Reference{Commit: commit, Topics: ReadingOrder(readme), Retired: RetiredWords(glossary), Lines: DaemonLines(daemonLinesFile)}
	if len(ref.Topics) == 0 {
		return nil, fmt.Errorf("hq's 02-DECISIONS/README.md at %s writes no reading order", short(commit))
	}
	if len(ref.Retired) == 0 {
		return nil, fmt.Errorf("hq's glossary at %s names no retired word: the words rule would pass on anything", short(commit))
	}
	return ref, nil
}

func short(commit string) string {
	if len(commit) > 12 {
		return commit[:12]
	}
	return commit
}

// ---- running prose ---------------------------------------------------------------------------------------

var (
	codeBlock  = regexp.MustCompile("(?ms)^\\s*```.*?^\\s*```")
	comment    = regexp.MustCompile(`(?s)<!--.*?-->`)
	blockQuote = regexp.MustCompile(`(?m)^\s*>.*$`)
	codeSpan   = regexp.MustCompile("`[^`\n]+`")
	linkTarget = regexp.MustCompile(`\]\([^)\s]*\)`)
	strike     = regexp.MustCompile(`~~[^~\n]+~~`)
	quoted     = regexp.MustCompile(`"[^"\n]*"`)
	curly      = regexp.MustCompile(`“[^”]*”`)
	single     = regexp.MustCompile(`‘[^’\n]*’`)
)

func blankOut(text string, res ...*regexp.Regexp) string {
	for _, re := range res {
		text = re.ReplaceAllStringFunc(text, func(m string) string {
			return strings.Map(func(r rune) rune {
				if r == '\n' {
					return r
				}
				return ' '
			}, m)
		})
	}
	return text
}

// Prose is the running prose of a text, as hq's words check reads it: code, comments, block quotes, quotations,
// struck-through words and link targets blanked.
func Prose(text string) string {
	return blankOut(text, codeBlock, comment, blockQuote, codeSpan, linkTarget, strike, quoted, curly, single)
}

// OwnWords is a text with what is not its own words blanked; code is kept, since a line to type is written there.
func OwnWords(text string) string {
	return blankOut(text, comment, blockQuote, linkTarget, strike, quoted, curly, single)
}

// wordPattern is a retired word matched whole and in any case, a space matching any run of space or hyphen, its
// plural matched as the word.
func wordPattern(word string) *regexp.Regexp {
	parts := strings.Fields(word)
	for i, p := range parts {
		parts[i] = regexp.QuoteMeta(p)
	}
	return regexp.MustCompile(`(?i)` + strings.Join(parts, `[\s-]+`) + `(?:e?s)?`)
}

func isWordRune(r rune) bool {
	return r == '-' || r == '_' || unicode.IsLetter(r) || unicode.IsDigit(r)
}

// wholeMatches are the matches of re in text that stand alone: no letter, digit, - or _ on either side.
func wholeMatches(re *regexp.Regexp, text string) []string {
	var out []string
	for _, loc := range re.FindAllStringIndex(text, -1) {
		before, after := rune(' '), rune(' ')
		if loc[0] > 0 {
			before = []rune(text[:loc[0]])[len([]rune(text[:loc[0]]))-1]
		}
		if loc[1] < len(text) {
			after = []rune(text[loc[1]:])[0]
		}
		if !isWordRune(before) && !isWordRune(after) {
			out = append(out, text[loc[0]:loc[1]])
		}
	}
	return out
}

// RetiredIn are the retired words a text uses in its running prose.
func (ref *Reference) RetiredIn(text string) []string {
	prose := Prose(text)
	var out []string
	for _, w := range ref.Retired {
		for _, m := range wholeMatches(wordPattern(w), prose) {
			out = append(out, strings.Join(strings.Fields(m), " "))
		}
	}
	return out
}

// LinesIn are the daemons' lines a text writes.
func (ref *Reference) LinesIn(text string) []string {
	own := OwnWords(text)
	var out []string
	for _, l := range ref.Lines {
		d, c := regexp.QuoteMeta(l.Daemon), regexp.QuoteMeta(l.Command)
		var re *regexp.Regexp
		if l.WithArgument {
			re = regexp.MustCompile(`(?m)(?:^|` + "`" + `)[ \t]*(?:\$[ \t]*)?` + d + `\s+` + c + `\s+[^\s` + "`" + `]`)
			if re.MatchString(own) {
				out = append(out, l.Daemon+" "+l.Command)
			}
			continue
		}
		if len(wholeMatches(regexp.MustCompile(d+`\s+`+c), own)) > 0 {
			out = append(out, l.Daemon+" "+l.Command)
		}
	}
	return out
}