module BomForecastApi

# File lib/bom_forecast_api.rb, line 16
def fetch_daily(grid, timezone, date, fetch:)
  date_text = date.is_a?(Date) ? date.iso8601 : date.to_s
  tz = URI.encode_www_form_component(timezone.to_s)
  path = "/forecasts/daily/#{grid["x"]}/#{grid["y"]}?timezone=#{tz}&fcstDate=#{date_text}"
  BomApi.fetch_json(path, fetch: fetch)
end

# File lib/bom_forecast_api.rb, line 136
def format_issued(issue_time, timezone)
  return "" unless issue_time

  zone = TZInfo::Timezone.get(timezone)
  period = zone.period_for_utc(issue_time.utc)
  abbr = period.abbreviation.to_s
  time_text = issue_time.strftime("%-l:%M %P").sub("am", "am").sub("pm", "pm")
  date_text = issue_time.strftime("%A %-d %B %Y")
  "Forecast issued at #{time_text} #{abbr} on #{date_text}."
rescue StandardError
  ""
end

# File lib/bom_forecast_api.rb, line 124
def format_period(local_date, issue_date:, timezone:)
  weekday = local_date.strftime("%A")
  if issue_date && local_date == issue_date
    "Forecast for the rest of #{weekday}"
  else
    local_date.strftime("%A %-d %B")
  end
rescue StandardError
  weekday
end

# File lib/bom_forecast_api.rb, line 90
def format_rainfall(precip)
  amount = precip["exceeding_50percentchance_total_mm"]
  return "0 mm" if amount.nil? || amount.to_f <= 0

  upper = amount.to_f
  upper == upper.round ? "0 to #{upper.round} mm" : "0 to #{upper} mm"
end

# File lib/bom_forecast_api.rb, line 99
def format_temp(value)
  return nil if value.nil?

  BomForecast.normalize_value("#{value} °C")
end

# File lib/bom_forecast_api.rb, line 116
def local_date_for(date_utc, timezone)
  zone = TZInfo::Timezone.get(timezone)
  zone.to_local(Time.parse(date_utc).utc).to_date
rescue StandardError
  Date.parse(date_utc.to_s[0, 10])
end

# File lib/bom_forecast_api.rb, line 23
def lookup(api_place, fetch:)
  issue_date = Date.today
  json = fetch_daily(api_place[:grid], api_place[:timezone], issue_date, fetch: fetch)
  parse_forecast(json, place_name: api_place[:name])
rescue StandardError
  nil
end

# File lib/bom_forecast_api.rb, line 51
def parse_day(entry, issue_date:, timezone:, index:)
  air = entry.dig("atm", "surf_air")
  return nil unless air

  local_date = local_date_for(entry["date_utc"], timezone)
  period = format_period(local_date, issue_date: issue_date, timezone: timezone)
  precip = air["precip"] || {}
  rain_chance = rain_chance_for(precip, rest_of_today: period.match?(/rest of/i))
  rainfall = format_rainfall(precip)
  weather = BomWeatherCodes.lookup(air.dig("weather", "icon_code"))
  description = weather[:precis]
  min = format_temp(air["temp_min_cel"])
  max = format_temp(air["temp_max_cel"])

  {
    period: period,
    condition: weather[:condition],
    min: min,
    max: max,
    rainfall: rainfall,
    rain_chance: rain_chance,
    description: description,
    summary: description
  }
end

# File lib/bom_forecast_api.rb, line 31
def parse_forecast(json, place_name:)
  daily = json.dig("fcst", "daily")
  return nil unless daily&.any?

  timezone = json.dig("meta", "local_timezone") || "Australia/Sydney"
  issue_time = parse_issue_time(json.dig("meta", "issue_time_utc"), timezone)
  issue_date = issue_time&.to_date

  days = daily.filter_map.with_index do |entry, index|
    parse_day(entry, issue_date: issue_date, timezone: timezone, index: index)
  end
  return nil if days.empty?

  {
    place: place_name.to_s,
    issued: format_issued(issue_time, timezone),
    days: days
  }
end

# File lib/bom_forecast_api.rb, line 106
def parse_issue_time(issue_time_utc, timezone)
  return nil if issue_time_utc.to_s.strip.empty?

  zone = TZInfo::Timezone.get(timezone)
  zone.to_local(Time.parse(issue_time_utc).utc)
rescue StandardError
  nil
end

# File lib/bom_forecast_api.rb, line 78
def rain_chance_for(precip, rest_of_today:)
  percent = if rest_of_today
              precip["any_restofday_probability_percent"] || precip["any_probability_percent"]
            else
              precip["any_probability_percent"]
            end
  return nil if percent.nil?

  "#{percent.round}%"
end