//go:build ignore

// genlect generates the EF temporal Sunday lectionary from missalemeum
// (Divinum Officium data), keyed by lectio's computed temporal-day slug.
// One-time; requires network. Run from the repo root:
//
//	go run scripts/genlect.go
//
// Writes internal/caldata/tridentine-lectionary.ini.
package main

import (
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"regexp"
	"sort"
	"strings"
	"time"

	"github.com/lukaszkasprzak/lectio/internal/caldata"
	"github.com/lukaszkasprzak/lectio/internal/calendar"
)

var citeRe = regexp.MustCompile(`\*([^*]+)\*`)

// bookCommaRe strips a stray comma between the book name and the first
// chapter ("4 Kings, 5:1-15" -> "4 Kings 5:1-15"), a missalemeum data glitch.
// The [^:] guard means it only fires before any chapter:verse, so legitimate
// multi-chapter commas ("Gen 1:1, 2:3") are left intact.
var bookCommaRe = regexp.MustCompile(`^([^:]*?),\s+(\d+:)`)

// chapDotRe rewrites a European-style "chapter. verse" separator to a colon
// ("John 20. 19-31" -> "John 20:19-31"), another missalemeum data glitch. It is
// applied only when the citation carries no colon at all, so disjoint verse
// groups in a normal citation ("Ps 62:2. 3-4") are never touched.
var chapDotRe = regexp.MustCompile(`(\d+)\.\s+(\d)`)

func cleanCite(s string) string {
	s = bookCommaRe.ReplaceAllString(strings.TrimSpace(s), "$1 $2")
	if !strings.Contains(s, ":") {
		s = chapDotRe.ReplaceAllString(s, "$1:$2")
	}
	return s
}

func fetchCitations(date string) (epistle, gospel string) {
	resp, err := http.Get("https://www.missalemeum.com/en/api/v5/proper/" + date)
	if err != nil {
		return
	}
	defer resp.Body.Close()
	var data []struct {
		Sections []struct {
			ID   string     `json:"id"`
			Body [][]string `json:"body"` // [[english, latin]]
		} `json:"sections"`
	}
	if json.NewDecoder(resp.Body).Decode(&data) != nil || len(data) == 0 {
		return
	}
	for _, s := range data[0].Sections {
		if len(s.Body) == 0 || len(s.Body[0]) == 0 {
			continue
		}
		m := citeRe.FindStringSubmatch(s.Body[0][0]) // english text carries *citation*
		if m == nil {
			continue
		}
		switch s.ID {
		case "Lectio":
			epistle = cleanCite(m[1])
		case "Evangelium":
			gospel = cleanCite(m[1])
		}
	}
	return
}

func main() {
	sel := calendar.DefaultSelection()
	sel.Form = "old"
	layers := []calendar.Layer{caldata.Tridentine()}
	lect := map[string][2]string{} // slug -> {epistle, gospel}

	start := time.Date(2024, 1, 1, 0, 0, 0, 0, time.UTC)
	end := time.Date(2028, 12, 31, 0, 0, 0, 0, time.UTC)
	seen := map[string]bool{}
	// Seasons whose weekdays may have PROPER Masses (else a ferial repeats the
	// preceding Sunday and is resolved by the CLI fallback, so we skip it).
	properFerial := map[calendar.Season]bool{
		calendar.Advent: true, calendar.Lent: true,
		calendar.Passiontide: true, calendar.Easter_: true,
	}
	for d := start; !d.After(end); d = d.AddDate(0, 0, 1) {
		day := calendar.Compute(d, sel, layers)
		if day.Observed.Layer != "temporal" { // a feast won -> its own propers
			continue
		}
		slug := day.Observed.Slug
		isSunday := d.Weekday() == time.Sunday
		if !isSunday && !properFerial[day.Season] {
			continue // green-season feria -> repeats the Sunday
		}
		if seen[slug] {
			continue
		}
		ep, gos := fetchCitations(d.Format("2006-01-02"))
		if ep == "" && gos == "" {
			continue
		}
		seen[slug] = true
		if !isSunday {
			// store only if the reading differs from the preceding Sunday's Mass
			sun := d.AddDate(0, 0, -int(d.Weekday()))
			if r, ok := lect[calendar.Compute(sun, sel, layers).Observed.Slug]; ok && r[0] == ep && r[1] == gos {
				continue // a repeat -> the CLI fallback handles it
			}
		}
		lect[slug] = [2]string{ep, gos}
		fmt.Fprintf(os.Stderr, "%s %-38s ep=%-22s go=%s\n", d.Format("2006-01-02"), slug, ep, gos)
	}

	slugs := make([]string, 0, len(lect))
	for s := range lect {
		slugs = append(slugs, s)
	}
	sort.Strings(slugs)
	var b strings.Builder
	b.WriteString("; EF (1962) temporal lectionary, keyed by lectio's computed temporal-day slug.\n")
	b.WriteString("; Generated from missalemeum (Divinum Officium). Epistle (first) + Gospel citations.\n")
	for _, s := range slugs {
		v := lect[s]
		fmt.Fprintf(&b, "\n[%s]\n", s)
		if v[0] != "" {
			fmt.Fprintf(&b, "first = %s\n", v[0])
		}
		if v[1] != "" {
			fmt.Fprintf(&b, "gospel = %s\n", v[1])
		}
	}
	if err := os.WriteFile("internal/caldata/tridentine-lectionary.ini", []byte(b.String()), 0o644); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	fmt.Fprintf(os.Stderr, "wrote %d temporal entries\n", len(lect))
}