How can I cross check a data frame if all possible combinations on it exist in another data frame of reference in R using dplyr?

I have two data frames.

The first one that contain all the possible combinations with their corresponding value and looks like this :

The second one that comes from the production line has two columns the date column that has grouped all the variables corresponding to their date and are concatenated :

I want to find all the combinations in the second data frame and to see if they match with any combinations in the first data frame.If a variable stands alone in the second data frame as Alpha in 2022-01-01 to give me the 0 and otherwise the value of the combination.

Ideally I want the resulted data frame to look like this :

How can I do this in R using dplyr ?

library(tidyverse)
first = c("Alpha","Alpha","Alpha","Beta","Beta","Corn","Hat")
second = c("Beta","Corn","Desk","Corn","Desk","Desk","Ian")
val = c(10,20,30,40,50,60,70)
df1 = tibble(first,second,val);df1
date = c(as.Date("2022-01-01"),as.Date("2022-02-01"))
var = c("Alpha","Beta,Corn,Fanta,Epsilon,George,Hat,Ian")
df2  = tibble(date,var);df2 

>Solution :

library(dplyr)
library(tidyr)
df2 %>% 
  separate_rows(var) %>%
  group_by(date) %>% 
  summarise(var = if(length(var) > 1) list(combn(var, 2,  \(x) 
   tibble(first = x[1], second = x[2]), simplify = FALSE) %>% 
    bind_rows) else 
  list(tibble(first = var, second = var)) ) %>% 
 unnest(var) %>%
 inner_join(df1, by = c("first", "second")) %>% 
 full_join(df2, by = "date") %>% 
 mutate(first = coalesce(first, var)) %>%
  unite(combn, first, second, sep = ", ") %>% 
 select(-var)

-output

# A tibble: 3 × 3
  date       combn        val
  <date>     <chr>      <dbl>
1 2022-02-01 Beta, Corn    40
2 2022-02-01 Hat, Ian      70
3 2022-01-01 Alpha, NA     NA