@spec available_pairs(price_db()) :: [{String.t(), String.t()}]

Returns all available commodity pairs in the price database.

Examples

iex> db = %{{"EUR", "CHF"} => [...], {"USD", "CHF"} => [...]}
iex> Price.available_pairs(db)
[{"EUR", "CHF"}, {"USD", "CHF"}]

@spec build_price_db([price_directive()]) :: price_db()

Builds a price database from a list of price directives.

The database is indexed by {source_commodity, target_commodity} tuples, with prices sorted by date descending for efficient lookup.

Examples

iex> prices = [
...>   %{date: ~D[2026-01-15], commodity: "EUR", price: %{value: 0.9432, currency: "CHF"}},
...>   %{date: ~D[2026-02-01], commodity: "EUR", price: %{value: 0.9455, currency: "CHF"}}
...> ]
iex> db = Price.build_price_db(prices)
iex> db[{"EUR", "CHF"}]
[{~D[2026-02-01], 0.9455}, {~D[2026-01-15], 0.9432}]

@spec commodities_convertible_to(String.t(), price_db()) :: [String.t()]

Returns all commodities that can be converted to the target currency.

Examples

iex> db = %{{"EUR", "CHF"} => [...], {"USD", "CHF"} => [...], {"GBP", "EUR"} => [...]}
iex> Price.commodities_convertible_to("CHF", db)
["EUR", "USD"]

@spec extract_price_directives(String.t()) :: [price_directive()]

Extracts all price directives from input.

Returns a list of price directive maps with date, commodity, and price.

Examples

iex> input = """
...> P 2026-01-15 EUR CHF 0.9432
...> P 2026-01-15 USD CHF 0.8821
...> """
iex> Price.extract_price_directives(input)
[
  %{date: ~D[2026-01-15], commodity: "EUR", price: %{value: 0.9432, currency: "CHF", currency_position: :leading}},
  %{date: ~D[2026-01-15], commodity: "USD", price: %{value: 0.8821, currency: "CHF", currency_position: :leading}}
]

@spec lookup_price(String.t(), String.t(), Date.t(), price_db()) ::
  {:ok, Decimal.t()} | {:error, :no_price_found}

Looks up the price for a commodity on a given date.

Returns the most recent price on or before the given date.

Examples

iex> db = %{{"EUR", "CHF"} => [{~D[2026-02-01], 0.9455}, {~D[2026-01-15], 0.9432}]}
iex> Price.lookup_price("EUR", "CHF", ~D[2026-01-20], db)
{:ok, 0.9432}

iex> Price.lookup_price("EUR", "CHF", ~D[2026-02-15], db)
{:ok, 0.9455}

iex> Price.lookup_price("EUR", "CHF", ~D[2026-01-01], db)
{:error, :no_price_found}

@spec parse_price_directive(String.t()) :: {:ok, price_directive()} | :skip

Parses a single price directive line.

Format: P DATE COMMODITY PRICE

• DATE: YYYY/MM/DD or YYYY-MM-DD
• COMMODITY: The source commodity symbol (e.g., EUR, USD, AAPL)
• PRICE: The price amount with target currency (e.g., CHF 0.9432 or $150.00)

Examples

iex> Price.parse_price_directive("P 2026-01-15 EUR CHF 0.9432")
{:ok, %{date: ~D[2026-01-15], commodity: "EUR", price: %{value: 0.9432, currency: "CHF", currency_position: :leading}}}

iex> Price.parse_price_directive("P 2026/01/15 AAPL $150.00")
{:ok, %{date: ~D[2026-01-15], commodity: "AAPL", price: %{value: 150.0, currency: "$", currency_position: :leading}}}