// Package i18n holds the translations for everything prognosis writes itself:
// column headers, condition names, section labels, weekday and month names, and
// pollen species and bands.
//
// What is deliberately NOT translated: the body of an IMGW warning. IMGW
// publishes those in Polish only, and rendering an invented English version of
// an official warning would be worse than showing the original. In English mode
// the surrounding labels are English and the warning text stays Polish.
package i18n

import (
	"fmt"
	"time"
)

// Lang is a supported display language.
type Lang string

const (
	EN Lang = "en"
	PL Lang = "pl"
)

// Catalog is the set of strings for one language.
type Catalog struct {
	lang Lang

	// Table headers, keyed by column name.
	headers map[string]string
	// WMO weather code descriptions.
	conditions map[int]string
	// Section labels and short words.
	words map[string]string
	// Pollen taxa.
	species map[string]string
	// Qualitative pollen levels.
	bands map[string]string

	weekdays [7]string
	months   [12]string
}

var catalogs = map[Lang]*Catalog{EN: english(), PL: polish()}

// For returns the catalogue for a language, falling back to English so a
// mistyped language degrades to readable output rather than empty strings.
func For(lang string) *Catalog {
	if c, ok := catalogs[Lang(lang)]; ok {
		return c
	}
	return catalogs[EN]
}

// Lang reports which language this catalogue is.
func (c *Catalog) Lang() Lang { return c.lang }

// Header is the column heading for a column name.
func (c *Catalog) Header(column string) string {
	if s, ok := c.headers[column]; ok {
		return s
	}
	return column
}

// Condition describes a WMO weather code. Unknown codes are reported as such
// rather than silently blank, so a new code in the API is visible.
func (c *Catalog) Condition(code int) string {
	if s, ok := c.conditions[code]; ok {
		return s
	}
	return fmt.Sprintf("code %d", code)
}

// Word returns a label such as "day", "pollen" or "warnings".
func (c *Catalog) Word(key string) string {
	if s, ok := c.words[key]; ok {
		return s
	}
	return key
}

// Species is the display name of a pollen taxon.
func (c *Catalog) Species(name string) string {
	if s, ok := c.species[name]; ok {
		return s
	}
	return name
}

// Band is the display name of a qualitative pollen level.
func (c *Catalog) Band(key string) string {
	if s, ok := c.bands[key]; ok {
		return s
	}
	return key
}

// Date formats a date as "Mon 10 Aug" in the catalogue's language. Go's time
// package has no locale support, so the names come from the catalogue.
func (c *Catalog) Date(t time.Time) string {
	return fmt.Sprintf("%s %02d %s", c.weekdays[int(t.Weekday())], t.Day(), c.months[int(t.Month())-1])
}

func english() *Catalog {
	return &Catalog{
		lang: EN,
		headers: map[string]string{
			"hour": "hr", "icon": "", "temp": "temp", "feels": "feels",
			"conditions": "conditions", "mm": "mm", "rain": "rain",
			"wind": "wind", "gusts": "gusts", "dir": "dir",
			"humidity": "hum", "dew": "dew", "uv": "uv",
			"cloud": "cloud", "pressure": "hPa", "visibility": "vis",
		},
		conditions: map[int]string{
			0: "clear", 1: "mainly clear", 2: "part cloudy", 3: "overcast",
			45: "fog", 48: "rime fog",
			51: "lt drizzle", 53: "drizzle", 55: "hvy drizzle",
			56: "frz drizzle", 57: "frz drizzle",
			61: "lt rain", 63: "rain", 65: "hvy rain",
			66: "frz rain", 67: "frz rain",
			71: "lt snow", 73: "snow", 75: "hvy snow", 77: "snow grains",
			80: "lt showers", 81: "showers", 82: "hvy showers",
			85: "snow showers", 86: "hvy snow showers",
			95: "thunderstorm", 96: "storm + hail", 99: "storm + hail",
		},
		words: map[string]string{
			"sun": "sun", "up": "up", "down": "down",
			"day": "day", "dry": "dry", "pollen": "pollen",
			"rainfall": "rain", "over": "over", "daylight": "daylight",
			"of": "of", "max": "max", "level": "level",
			"warnings": "warnings", "could_not_check": "could not check IMGW",
			"poland_only":     "IMGW covers Poland only",
			"hours_available": "hours available, not",
			"h_per_col":       "h/col", "temp_row": "temp", "rain_row": "rain",
		},
		species: map[string]string{
			"grass": "grass", "birch": "birch", "alder": "alder",
			"mugwort": "mugwort", "ragweed": "ragweed", "olive": "olive",
		},
		bands: map[string]string{
			"none": "none", "low": "low", "medium": "medium",
			"high": "high", "very high": "very high",
		},
		weekdays: [7]string{"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"},
		months: [12]string{"Jan", "Feb", "Mar", "Apr", "May", "Jun",
			"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"},
	}
}

func polish() *Catalog {
	return &Catalog{
		lang: PL,
		headers: map[string]string{
			"hour": "godz", "icon": "", "temp": "temp", "feels": "odczuw",
			"conditions": "warunki", "mm": "mm", "rain": "deszcz",
			"wind": "wiatr", "gusts": "porywy", "dir": "kier",
			"humidity": "wilg", "dew": "ros", "uv": "uv",
			"cloud": "chmury", "pressure": "hPa", "visibility": "wid",
		},
		// Terminology follows IMGW's own vocabulary where it has one, so the
		// table and a warning describe the same weather in the same words.
		conditions: map[int]string{
			0: "bezchmurnie", 1: "gł. bezchmurnie", 2: "częśc. zachm.", 3: "zachmurzenie",
			45: "mgła", 48: "mgła osadz.",
			51: "słaba mżawka", 53: "mżawka", 55: "silna mżawka",
			56: "mżawka marzn.", 57: "mżawka marzn.",
			61: "słaby deszcz", 63: "deszcz", 65: "silny deszcz",
			66: "deszcz marzn.", 67: "deszcz marzn.",
			71: "słaby śnieg", 73: "śnieg", 75: "silny śnieg", 77: "ziarna śniegu",
			80: "słabe przelotne", 81: "przelotne", 82: "silne przelotne",
			85: "przelotny śnieg", 86: "silny przel. śnieg",
			95: "burza", 96: "burza z gradem", 99: "burza z gradem",
		},
		words: map[string]string{
			"sun": "słońce", "up": "wsch", "down": "zach",
			"day": "dzień", "dry": "sucho", "pollen": "pyłek",
			"rainfall": "opad", "over": "przez", "daylight": "dnia",
			"of": "z", "max": "maks", "level": "stopień",
			"warnings": "ostrzeżenia", "could_not_check": "nie udało się sprawdzić IMGW",
			"poland_only":     "IMGW obejmuje tylko Polskę",
			"hours_available": "godzin dostępnych, nie",
			"h_per_col":       "h/kol", "temp_row": "temp", "rain_row": "opad",
		},
		species: map[string]string{
			"grass": "trawy", "birch": "brzoza", "alder": "olcha",
			"mugwort": "bylica", "ragweed": "ambrozja", "olive": "oliwka",
		},
		bands: map[string]string{
			"none": "brak", "low": "niskie", "medium": "średnie",
			"high": "wysokie", "very high": "b. wysokie",
		},
		weekdays: [7]string{"nd", "pn", "wt", "śr", "cz", "pt", "sb"},
		months: [12]string{"sty", "lut", "mar", "kwi", "maj", "cze",
			"lip", "sie", "wrz", "paź", "lis", "gru"},
	}
}