// Command clectio-gen emits the compiled data for clectio, the tiny suckless-C
// daily-readings build. It reuses lectio's validated calendar + lectionary
// engine to compute, for every day in a year range, the day's name, colour, and
// readings -- then writes two artifacts:
//
//	liturgy_<form>.h : corpus-INDEPENDENT C tables (days, readings, citations,
//	                   and verse KEYS as indices) -- shipped, frozen.
//	verses_<form>.keys : the ordered (book,chapter,verse) keys, one per line --
//	                   shipped, resolved to text at clectio build time (mktext)
//	                   against whatever Vulgate-numbered corpus is compiled in.
//
// So the hard liturgical logic stays here (Go, oracle-validated); the C side is
// a dumb lookup + renderer, and swapping the Bible never touches this generator.
//
// Usage: clectio-gen [-caldir DIR -use NAMES] [-sanctorale DIR] <new|old> <startYear> <endYear> <outdir>
//
// By default it uses lectio's embedded, oracle-validated calendar. To bake a
// customized calendar into clectio, point it at calendar layers (-caldir with a
// comma-separated -use list) and/or a replacement sanctorale (-sanctorale DIR
// with of.ini/ef.ini). Only the calendar is taken from those; the book table
// stays embedded, so the generator never reads a stale user books.ini.
package main

import (
	"bufio"
	"flag"
	"fmt"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"time"

	"github.com/lukaszkasprzak/lectio/internal/bible"
	"github.com/lukaszkasprzak/lectio/internal/caldata"
	"github.com/lukaszkasprzak/lectio/internal/config"
	"github.com/lukaszkasprzak/lectio/internal/liturgy"
	"github.com/lukaszkasprzak/lectio/internal/readings"
)

// colourIndex maps a liturgical colour to the small enum clectio prints.
var colourIndex = map[string]int{
	"green": 0, "white": 1, "red": 2, "violet": 3, "rose": 4, "black": 5,
}

// partLabel is the English section label clectio prints, by PartID.
func partLabel(id string) string {
	switch id {
	case "pierwsze_czytanie":
		return "First Reading"
	case "psalm":
		return "Responsorial Psalm"
	case "drugie_czytanie":
		return "Second Reading"
	case "aklamacja":
		return "Gospel Acclamation"
	case "ewangelia", "evangelium":
		return "Gospel"
	case "epistola":
		return "Epistle"
	}
	switch {
	case strings.HasPrefix(id, "lectio"):
		return "Lesson"
	case strings.HasPrefix(id, "prophetia"):
		return "Prophecy"
	}
	return "Reading"
}

// intern assigns a stable index to each distinct string, preserving first-seen
// order.
type intern struct {
	idx  map[string]int
	list []string
}

func newIntern() *intern { return &intern{idx: map[string]int{}} }
func (n *intern) get(s string) int {
	if i, ok := n.idx[s]; ok {
		return i
	}
	i := len(n.list)
	n.idx[s] = i
	n.list = append(n.list, s)
	return i
}

// reading is one distinct pericope: its part label, citation in each sigla, and
// the verse-key indices that make it up.
type reading struct {
	part, citeEN, citeLA int
	verses               []int
}

// day is one distinct liturgy: its name, colour, and ordered reading indices.
type day struct {
	name, colour int
	readings     []int
}

func main() {
	caldir := flag.String("caldir", "", "directory of calendar-layer .ini files to apply (use with -use)")
	use := flag.String("use", "", "comma-separated layer names to stack over the calendar (needs -caldir)")
	sanctorale := flag.String("sanctorale", "", "directory with of.ini/ef.ini that REPLACE the embedded sanctorale")
	flag.Usage = func() {
		fmt.Fprintln(os.Stderr, "usage: clectio-gen [-caldir DIR -use NAMES] [-sanctorale DIR] <new|old> <startYear> <endYear> <outdir>")
		flag.PrintDefaults()
	}
	flag.Parse()
	args := flag.Args()
	if len(args) != 4 {
		flag.Usage()
		os.Exit(2)
	}
	// Hermetic BOOK table: point config at a nonexistent path so the generator
	// never reads the running user's ~/.config/lectio/books.ini (which could be
	// stale and silently drop readings). Calendar customization comes ONLY from
	// the explicit flags below, so the two concerns stay separate.
	os.Setenv("LECTIO_CONFIG", filepath.Join(os.TempDir(), "clectio-gen-no-such-dir", "config.ini"))
	if *caldir != "" {
		config.SetCalendarsDir(*caldir)
	}
	if *sanctorale != "" {
		caldata.SetSanctoraleDir(*sanctorale)
	}
	var useList []string
	if *use != "" {
		useList = strings.Split(*use, ",")
	}

	form := args[0] // "new" (OF) or "old" (EF)
	lect := "new"
	tag := "of"
	if form == "old" {
		lect, tag = "traditional", "ef"
	}
	y0, _ := strconv.Atoi(args[1])
	y1, _ := strconv.Atoi(args[2])
	outdir := args[3]

	base := func(sigla string) config.Config {
		c := config.Default()
		c.UILanguage = "en"
		c.Lectionary = lect
		c.SiglaStyle = sigla
		c.Use = useList
		return c
	}
	cfgEN, cfgLA := base("english"), base("latin")

	names := newIntern()
	parts := newIntern()
	citesEN := newIntern()
	citesLA := newIntern()
	verseKeys := newIntern() // key "Book\tChap\tVerse" -> verse index
	var readingList []reading
	readingIdx := map[string]int{}
	var dayList []day
	dayIdx := map[string]int{}
	var cal []int

	internReading := func(secEN, secLA liturgy.Section) int {
		keys := bible.LookupKeyed("vul", resolveRef(secEN, form))
		if len(keys) == 0 {
			return -1
		}
		vids := make([]int, len(keys))
		for i, k := range keys {
			vids[i] = verseKeys.get(fmt.Sprintf("%s\t%d\t%d", k.Book, k.Chapter, k.Verse))
		}
		r := reading{
			part:   parts.get(partLabel(secEN.PartID)),
			citeEN: citesEN.get(secEN.Citation),
			citeLA: citesLA.get(secLA.Citation),
			verses: vids,
		}
		key := fmt.Sprintf("%d|%d|%d|%v", r.part, r.citeEN, r.citeLA, vids)
		if i, ok := readingIdx[key]; ok {
			return i
		}
		i := len(readingList)
		readingIdx[key] = i
		readingList = append(readingList, r)
		return i
	}

	start := time.Date(y0, 1, 1, 0, 0, 0, 0, time.UTC)
	end := time.Date(y1, 12, 31, 0, 0, 0, 0, time.UTC)
	for d := start; !d.After(end); d = d.AddDate(0, 0, 1) {
		ds := d.Format("2006-01-02")
		secsEN, info, err := readings.Load(cfgEN, readings.Options{Date: ds, All: true})
		if err != nil {
			fmt.Fprintf(os.Stderr, "clectio-gen: %s: %v\n", ds, err)
			os.Exit(1)
		}
		secsLA, _, _ := readings.Load(cfgLA, readings.Options{Date: ds, All: true})

		var rids []int
		for i, secEN := range secsEN {
			secLA := secEN
			if i < len(secsLA) {
				secLA = secsLA[i]
			}
			if id := internReading(secEN, secLA); id >= 0 {
				rids = append(rids, id)
			} else {
				fmt.Fprintf(os.Stderr, "clectio-gen: %s DROP part=%s ref=%q cite=%q\n",
					ds, secEN.PartID, resolveRef(secEN, form), secEN.Citation)
			}
		}
		dy := day{
			name:     names.get(info.Name),
			colour:   colourIndex[info.Colour],
			readings: rids,
		}
		key := fmt.Sprintf("%d|%d|%v", dy.name, dy.colour, rids)
		id, ok := dayIdx[key]
		if !ok {
			id = len(dayList)
			dayIdx[key] = id
			dayList = append(dayList, dy)
		}
		cal = append(cal, id)
	}

	if err := os.MkdirAll(outdir, 0o755); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	writeKeys(filepath.Join(outdir, "verses_"+tag+".keys"), verseKeys.list)
	writeHeader(filepath.Join(outdir, "liturgy_"+tag+".h"), tag, y0,
		names.list, parts.list, citesEN.list, citesLA.list, readingList, dayList, cal)
	fmt.Printf("clectio-gen %s: %d days, %d distinct days, %d readings, %d verses\n",
		tag, len(cal), len(dayList), len(readingList), len(verseKeys.list))
}

// resolveRef mirrors render.resolveRef: prefer the English-canonical Ref, and
// for the Ordinary Form renumber the Psalms to the Vulgate the keys come from.
func resolveRef(sec liturgy.Section, form string) string {
	cit := sec.Ref
	if cit == "" {
		cit = sec.Citation
	}
	if cit == "" {
		if c, err := liturgy.ExtractCitation(sec.Heading); err == nil {
			cit = c
		}
	}
	if cit == "" {
		return ""
	}
	if form != "new" {
		return cit // EF citations are already Vulgate-numbered
	}
	return bible.OFRef(cit, "vulgate")
}

func writeKeys(path string, keys []string) {
	f, err := os.Create(path)
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	defer f.Close()
	w := bufio.NewWriter(f)
	for _, k := range keys {
		w.WriteString(k + "\n")
	}
	w.Flush()
}

func cstr(s string) string {
	r := strings.NewReplacer(`\`, `\\`, `"`, `\"`, "\t", `\t`)
	return `"` + r.Replace(s) + `"`
}

func writeHeader(path, tag string, y0 int, names, parts, citesEN, citesLA []string,
	readings []reading, days []day, cal []int) {
	f, err := os.Create(path)
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	defer f.Close()
	w := bufio.NewWriter(f)
	defer w.Flush()

	guard := "LITURGY_" + strings.ToUpper(tag) + "_H"
	fmt.Fprintf(w, "/* generated by clectio-gen -- do not edit */\n#ifndef %s\n#define %s\n\n", guard, guard)
	fmt.Fprintf(w, "#define EPOCH_Y %d\n#define EPOCH_M 1\n#define EPOCH_D 1\n#define NDAYS %d\n\n", y0, len(cal))

	strArr := func(name string, xs []string) {
		fmt.Fprintf(w, "static const char *const %s[] = {\n", name)
		for _, s := range xs {
			fmt.Fprintf(w, "\t%s,\n", cstr(s))
		}
		fmt.Fprintf(w, "};\n\n")
	}
	strArr("names", names)
	strArr("parts", parts)
	strArr("cites_en", citesEN)
	strArr("cites_la", citesLA)

	// Flat verse-index pool; each reading points at a [voff,voff+vlen) slice.
	var vpool []int
	fmt.Fprintf(w, "static const unsigned short vpool[] = {")
	for _, r := range readings {
		for _, v := range r.verses {
			vpool = append(vpool, v)
		}
	}
	for i, v := range vpool {
		if i%16 == 0 {
			fmt.Fprintf(w, "\n\t")
		}
		fmt.Fprintf(w, "%d,", v)
	}
	fmt.Fprintf(w, "\n};\n\n")

	fmt.Fprintf(w, "typedef struct { unsigned short part, cite, voff, vlen; } Reading;\n")
	fmt.Fprintf(w, "static const Reading readings[] = {\n")
	voff := 0
	for _, r := range readings {
		fmt.Fprintf(w, "\t{%d,%d,%d,%d},\n", r.part, r.citeEN, voff, len(r.verses))
		voff += len(r.verses)
	}
	fmt.Fprintf(w, "};\n\n")
	// cite_la parallels readings[] by index (same part/verses, latin citation).
	fmt.Fprintf(w, "static const unsigned short readings_cite_la[] = {")
	for i, r := range readings {
		if i%16 == 0 {
			fmt.Fprintf(w, "\n\t")
		}
		fmt.Fprintf(w, "%d,", r.citeLA)
	}
	fmt.Fprintf(w, "\n};\n\n")

	// Flat reading-index pool; each day points at a [roff,roff+rlen) slice.
	var rpool []int
	fmt.Fprintf(w, "static const unsigned short rpool[] = {")
	for _, d := range days {
		for _, r := range d.readings {
			rpool = append(rpool, r)
		}
	}
	for i, r := range rpool {
		if i%16 == 0 {
			fmt.Fprintf(w, "\n\t")
		}
		fmt.Fprintf(w, "%d,", r)
	}
	fmt.Fprintf(w, "\n};\n\n")

	fmt.Fprintf(w, "typedef struct { unsigned short name; unsigned char colour; unsigned short roff, rlen; } Day;\n")
	fmt.Fprintf(w, "static const Day days[] = {\n")
	roff := 0
	for _, d := range days {
		fmt.Fprintf(w, "\t{%d,%d,%d,%d},\n", d.name, d.colour, roff, len(d.readings))
		roff += len(d.readings)
	}
	fmt.Fprintf(w, "};\n\n")

	fmt.Fprintf(w, "static const unsigned short cal[NDAYS] = {")
	for i, c := range cal {
		if i%16 == 0 {
			fmt.Fprintf(w, "\n\t")
		}
		fmt.Fprintf(w, "%d,", c)
	}
	fmt.Fprintf(w, "\n};\n\n#endif\n")
}