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import gleam/io
import gleam/int
import gleam/list
import gleam/pair
import gleam/result as res
import gleam/function as fun
import gleam/dict.{type Dict}
import gleam/iterator.{type Iterator} as iter
import ext/genericx as genx
import ext/resultx as resx
import ext/iteratorx as iterx
import util/graph
import util/input_util
import util/parser as p
const special_bag = "shiny gold"
type BagId =
String
type BagEdge =
#(BagId, Int)
type BagGraph =
Dict(BagId, List(BagEdge))
type BagNeighbourFun =
fn(BagId) -> Iterator(BagId)
fn parse_graph(lines: List(String)) -> BagGraph {
let bag_type_parser =
[p.str1_until_ws(), p.ws_gc(), p.str1_until_ws()]
|> p.str_of_seq
|> p.labeled(with: "bag_type")
let line_parser =
bag_type_parser
|> p.skip(p.literal(" bags contain "))
|> p.then(p.or(
p.int()
|> p.skip_ws
|> p.then(bag_type_parser)
|> p.map(with: pair.swap)
|> p.skip_ws
|> p.skip(p.then(p.literal("bag"), p.opt(p.literal("s"))))
|> p.sep1(by: p.literal(", ")),
otherwise: p.literal("no other bags")
|> p.replace(with: []),
))
|> p.skip(p.literal("."))
lines
|> list.map(with: fun.compose(
p.parse_entire(_, with: line_parser),
resx.assert_unwrap,
))
|> dict.from_list
}
fn neighbour_fun(graph: BagGraph) -> BagNeighbourFun {
fn(bag) {
graph
|> dict.get(bag)
|> resx.assert_unwrap
|> list.map(with: pair.first)
|> iter.from_list
}
}
fn bag_count(of bag: BagId, in graph: BagGraph) -> Int {
list.fold(
over: graph
|> dict.get(bag)
|> res.unwrap(or: []),
from: 1,
with: fn(sum, edge) {
let #(next_bag, next_count) = edge
sum + next_count * bag_count(of: next_bag, in: graph)
},
)
}
fn part1(lines: List(String)) -> Int {
let graph = parse_graph(lines)
let neighbours = neighbour_fun(graph)
graph
|> dict.keys
|> iter.from_list
|> iter.filter(keeping: genx.different(_, than: special_bag))
|> iterx.count(satisfying: fn(start) {
start
|> graph.dfs(with: neighbours)
|> iter.any(satisfying: genx.equals(_, special_bag))
})
}
fn part2(lines: List(String)) -> Int {
special_bag
|> bag_count(in: parse_graph(lines))
|> int.subtract(1)
}
pub fn main() -> Nil {
let testing = input_util.read_lines("test07")
let assert 4 = part1(testing)
let assert 32 = part2(testing)
let input = input_util.read_lines("day07")
io.debug(part1(input))
io.debug(part2(input))
Nil
}
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