// Package mobile is lectio's engine facade for the dlectio Android app. It is
// bound to a native Android library with gomobile:
//
//	gomobile bind -target=android/arm64,android/amd64 -androidapi 26 \
//	  -javapkg=xyz.labunix.dlectio.engine -tags fullbible \
//	  -o dlectio-engine.aar github.com/lukaszkasprzak/lectio/mobile
//
// -javapkg gives the bound Mobile class its xyz.labunix.dlectio.engine.mobile
// package (the app imports it from there); the two -target ABIs match the
// app's arm64-v8a and x86_64 device/emulator targets; -androidapi 26 matches
// the app's minSdk. Omitting any of the three still produces an .aar, just
// one the app cannot import or that lacks an ABI it needs.
//
// The app calls Day() with a plain date/form/version and receives one JSON
// document with the day's identity and rendered Mass readings. All liturgical
// computation and text resolution happens here, in the exact validated lectio
// engine — the app does none of it. Keep every exported signature to types
// gomobile can marshal -- strings and ints only -- with JSON as the payload
// format for everything structured. A Go int parameter (e.g. Days' count)
// surfaces on the Kotlin side as a long, not an Int.
package mobile

import (
	"encoding/json"
	"strings"
	"time"

	"github.com/lukaszkasprzak/lectio/internal/config"
	"github.com/lukaszkasprzak/lectio/internal/i18n"
	"github.com/lukaszkasprzak/lectio/internal/readings"
	"github.com/lukaszkasprzak/lectio/internal/render"
)

// reading is one Mass reading, rendered in the requested corpus.
type reading struct {
	Ord      int    `json:"ord"`
	Part     string `json:"part"`    // machine key, e.g. "ewangelium" / "psalm"
	Heading  string `json:"heading"` // human label in the interface language, e.g. "Gospel"
	Citation string `json:"citation"`
	Text     string `json:"text"`
}

// dayDoc is the JSON returned by Day.
type dayDoc struct {
	Date      string    `json:"date"`
	Form      string    `json:"form"`
	Lang      string    `json:"lang"`
	Version   string    `json:"version"`
	Name      string    `json:"name"`
	Season    string    `json:"season"`
	Colour    string    `json:"colour"`
	Rank      string    `json:"rank"`
	RankLabel string    `json:"rank_label"`
	Readings  []reading `json:"readings"`
	Error     string    `json:"error,omitempty"`
}

// lectByForm maps the app's form code to lectio's lectionary value.
func lectByForm(form string) string {
	if form == "ef" {
		return "traditional"
	}
	return "new"
}

// Day computes one day's identity and Mass readings and returns them as JSON.
//
//	date    - "YYYY-MM-DD"
//	form    - "of" (Ordinary) or "ef" (1962)
//	version - corpus: "drb" | "wuj" | "vul" | "grb"
//	lang    - interface language for the celebration name: "en" | "pl"
//
// It never panics: any engine error is reported in the JSON "error" field so the
// JNI boundary always returns a well-formed string.
func Day(date, form, version, lang string) string {
	lect := lectByForm(form)
	out := dayDoc{Date: date, Form: form, Lang: lang, Version: version}

	// Day identity (name/season/colour) in the interface language.
	cfgID := config.Config{UILanguage: lang, Lectionary: lect, All: true}
	if _, info, err := readings.Load(cfgID, readings.Options{Date: date, All: true}); err == nil {
		out.Name = info.Name
		out.Season = info.Season
		out.Colour = info.Colour
		out.Rank = info.Rank
		out.RankLabel = i18n.Get(lang).Rank[info.Rank]
	} else {
		out.Error = err.Error()
	}

	// Readings, resolved and rendered in the requested corpus. The interface
	// language localizes the structural labels (Heading) and citation dialect;
	// the corpus (version) alone decides the scripture text.
	cfgR := config.Config{UILanguage: lang, Lectionary: lect, ReadingVersion: version, All: true}
	secs, _, err := readings.Load(cfgR, readings.Options{Date: date, All: true})
	if err != nil {
		if out.Error == "" {
			out.Error = err.Error()
		}
	} else {
		for i, sec := range secs {
			// GatherVersion's lang localizes only the label/error wording, never
			// the verse text (which the corpus alone decides), so the interface
			// language is correct here. HeadingWithRef gives the same localized
			// "label (citation)" heading lectio shows in its cli/tui/web.
			_, blocks := render.GatherVersion(version, sec, lect, lang)
			out.Readings = append(out.Readings, reading{
				Ord:      i,
				Part:     sec.PartID,
				Heading:  render.HeadingWithRef(sec, lang),
				Citation: sec.Citation,
				Text:     strings.Join(blocks, "\n"),
			})
		}
	}

	b, err := json.Marshal(out)
	if err != nil {
		// Should be impossible with these types; degrade gracefully.
		return `{"error":"marshal failed"}`
	}
	return string(b)
}

// summaryPart is one section of a day, citation only -- no rendered text.
type summaryPart struct {
	Part     string `json:"part"`
	Citation string `json:"citation"`
}

// daySummary is one day's identity and its reading citations. It is Day's
// cheaper projection: the calendar view needs the day's shape, not its text.
type daySummary struct {
	Date      string        `json:"date"`
	Name      string        `json:"name"`
	Rank      string        `json:"rank"`
	RankLabel string        `json:"rank_label"`
	Colour    string        `json:"colour"`
	Parts     []summaryPart `json:"parts"`
	Error     string        `json:"error,omitempty"`
}

// Days returns count consecutive days from start as a JSON array, each with its
// identity and reading citations but no reading text. It is the calendar view's
// source.
//
//	start - "YYYY-MM-DD", taken literally: aligning to a week is the caller's job
//	count - 1..366; anything else yields "[]"
//	form  - "of" or "ef"
//	lang  - interface language for the name, rank word and citation dialect
//
// No version parameter: the corpus decides only scripture text, which this never
// renders, while the citation's sigla dialect follows lang.
//
// A day that fails to compute carries its own "error" and does not abort the
// rest, so one bad date cannot blank a whole week. Malformed input yields "[]"
// rather than an error string, so the caller always parses an array.
func Days(start string, count int, form, lang string) string {
	if count < 1 || count > 366 {
		return "[]"
	}
	d, err := time.Parse("2006-01-02", start)
	if err != nil {
		return "[]"
	}
	lect := lectByForm(form)
	ui := i18n.Get(lang)
	cfg := config.Config{UILanguage: lang, Lectionary: lect, All: true}

	out := make([]daySummary, 0, count)
	for i := 0; i < count; i++ {
		date := d.AddDate(0, 0, i).Format("2006-01-02")
		row := daySummary{Date: date, Parts: []summaryPart{}}
		secs, info, err := readings.Load(cfg, readings.Options{Date: date, All: true})
		if err != nil {
			row.Error = err.Error()
		} else {
			row.Name = info.Name
			row.Colour = info.Colour
			row.Rank = info.Rank
			row.RankLabel = ui.Rank[info.Rank]
			for _, sec := range secs {
				row.Parts = append(row.Parts, summaryPart{Part: sec.PartID, Citation: sec.Citation})
			}
		}
		out = append(out, row)
	}

	b, err := json.Marshal(out)
	if err != nil {
		return "[]"
	}
	return string(b)
}

// partLabel is one section's machine ID and its human label.
type partLabel struct {
	Part  string `json:"part"`
	Label string `json:"label"`
}

// PartLabels returns the form's section IDs and their labels in lang, in display
// order, as a JSON array. The app builds its reading filters from this instead
// of hardcoding part IDs -- which is how it came to ship seven 1962 checkboxes
// the engine never emits.
//
// An array, not an object: JSON object key order is not guaranteed and the app
// renders these in order.
func PartLabels(form, lang string) string {
	ids := readings.PartIDs(lectByForm(form))
	ui := i18n.Get(lang)
	out := make([]partLabel, 0, len(ids))
	for _, id := range ids {
		label := ui.PartLabel[id]
		if label == "" {
			label = id
		}
		out = append(out, partLabel{Part: id, Label: label})
	}
	b, err := json.Marshal(out)
	if err != nil {
		return "[]"
	}
	return string(b)
}

// Ping is a trivial JNI smoke test: it returns "pong" so the app can confirm the
// native engine loaded before issuing a real query.
func Ping() string { return "pong" }