feat(float): implement footer

Problem: Now way to show text at the bottom part of floating window
  border (a.k.a. "footer").

Solution: Allows `footer` and `footer_pos` config fields similar to
  `title` and `title_pos`.

1 files changed, 395 insertions, 0 deletions

diff --git a/test/functional/ui/float_spec.lua b/test/functional/ui/float_spec.lua
index 85795e7e17..6cdd6e51fa 100644
--- a/test/functional/ui/float_spec.lua
+++ b/test/functional/ui/float_spec.lua
@@ -1851,6 +1851,39 @@ describe('float window', function()
       eq('center', title_pos)
     end)
 
+    it('validates footer footer_pos', function()
+      local buf = meths.create_buf(false,false)
+      eq("footer requires border to be set",
+         pcall_err(meths.open_win,buf, false, {
+          relative='editor', width=9, height=2, row=2, col=5, footer='Footer',
+         }))
+      eq("footer_pos requires footer to be set",
+         pcall_err(meths.open_win,buf, false, {
+          relative='editor', width=9, height=2, row=2, col=5,
+          border='single', footer_pos='left',
+         }))
+    end)
+
+    it('validate footer_pos in nvim_win_get_config', function()
+      local footer_pos = exec_lua([[
+        local bufnr = vim.api.nvim_create_buf(false, false)
+        local opts = {
+          relative = 'editor',
+          col = 2,
+          row = 5,
+          height = 2,
+          width = 9,
+          border = 'double',
+          footer = 'Test',
+          footer_pos = 'center'
+        }
+
+        local win_id = vim.api.nvim_open_win(bufnr, true, opts)
+        return vim.api.nvim_win_get_config(win_id).footer_pos
+      ]])
+
+      eq('center', footer_pos)
+    end)
 
     it('border with title', function()
       local buf = meths.create_buf(false, false)
@@ -2033,6 +2066,368 @@ describe('float window', function()
       end
     end)
 
+    it('border with footer', function()
+      local buf = meths.create_buf(false, false)
+      meths.buf_set_lines(buf, 0, -1, true, {' halloj! ',
+                                             ' BORDAA  '})
+      local win = meths.open_win(buf, false, {
+        relative='editor', width=9, height=2, row=2, col=5, border="double",
+        footer = "Left",footer_pos = "left",
+      })
+
+      if multigrid then
+        screen:expect{grid=[[
+        ## grid 1
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [3:----------------------------------------]|
+        ## grid 2
+          ^                                        |
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+        ## grid 3
+                                                  |
+        ## grid 4
+          {5:╔═════════╗}|
+          {5:║}{1: halloj! }{5:║}|
+          {5:║}{1: BORDAA  }{5:║}|
+          {5:╚}{11:Left}{5:═════╝}|
+        ]], float_pos={
+          [4] = { { id = 1001 }, "NW", 1, 2, 5, true }
+        }, win_viewport={
+          [2] = {win = {id = 1000}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 1, sum_scroll_delta = 0};
+          [4] = {win = {id = 1001}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 2, sum_scroll_delta = 0};
+        }}
+      else
+        screen:expect{grid=[[
+          ^                                        |
+          {0:~                                       }|
+          {0:~    }{5:╔═════════╗}{0:                        }|
+          {0:~    }{5:║}{1: halloj! }{5:║}{0:                        }|
+          {0:~    }{5:║}{1: BORDAA  }{5:║}{0:                        }|
+          {0:~    }{5:╚}{11:Left}{5:═════╝}{0:                        }|
+                                                  |
+        ]]}
+      end
+
+      meths.win_set_config(win, {footer= "Center",footer_pos="center"})
+      if multigrid then
+        screen:expect{grid=[[
+        ## grid 1
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [3:----------------------------------------]|
+        ## grid 2
+          ^                                        |
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+        ## grid 3
+                                                  |
+        ## grid 4
+          {5:╔═════════╗}|
+          {5:║}{1: halloj! }{5:║}|
+          {5:║}{1: BORDAA  }{5:║}|
+          {5:╚═}{11:Center}{5:══╝}|
+        ]], float_pos={
+          [4] = { { id = 1001 }, "NW", 1, 2, 5, true }
+        }, win_viewport={
+          [2] = {win = {id = 1000}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 1, sum_scroll_delta = 0};
+          [4] = {win = {id = 1001}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 2, sum_scroll_delta = 0};
+        }}
+      else
+        screen:expect{grid=[[
+          ^                                        |
+          {0:~                                       }|
+          {0:~    }{5:╔═════════╗}{0:                        }|
+          {0:~    }{5:║}{1: halloj! }{5:║}{0:                        }|
+          {0:~    }{5:║}{1: BORDAA  }{5:║}{0:                        }|
+          {0:~    }{5:╚═}{11:Center}{5:══╝}{0:                        }|
+                                                  |
+        ]]}
+      end
+
+      meths.win_set_config(win, {footer= "Right",footer_pos="right"})
+      if multigrid then
+        screen:expect{grid=[[
+        ## grid 1
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [3:----------------------------------------]|
+        ## grid 2
+          ^                                        |
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+        ## grid 3
+                                                  |
+        ## grid 4
+          {5:╔═════════╗}|
+          {5:║}{1: halloj! }{5:║}|
+          {5:║}{1: BORDAA  }{5:║}|
+          {5:╚════}{11:Right}{5:╝}|
+        ]], float_pos={
+          [4] = { { id = 1001 }, "NW", 1, 2, 5, true }
+        }, win_viewport={
+          [2] = {win = {id = 1000}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 1, sum_scroll_delta = 0};
+          [4] = {win = {id = 1001}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 2, sum_scroll_delta = 0};
+        }}
+      else
+        screen:expect{grid=[[
+          ^                                        |
+          {0:~                                       }|
+          {0:~    }{5:╔═════════╗}{0:                        }|
+          {0:~    }{5:║}{1: halloj! }{5:║}{0:                        }|
+          {0:~    }{5:║}{1: BORDAA  }{5:║}{0:                        }|
+          {0:~    }{5:╚════}{11:Right}{5:╝}{0:                        }|
+                                                  |
+        ]]}
+      end
+
+      meths.win_set_config(win, {footer= { {"🦄"},{"BB"}},footer_pos="right"})
+      if multigrid then
+        screen:expect{grid=[[
+        ## grid 1
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [3:----------------------------------------]|
+        ## grid 2
+          ^                                        |
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+        ## grid 3
+                                                  |
+        ## grid 4
+          {5:╔═════════╗}|
+          {5:║}{1: halloj! }{5:║}|
+          {5:║}{1: BORDAA  }{5:║}|
+          {5:╚═════}🦄BB{5:╝}|
+        ]], float_pos={
+          [4] = { { id = 1001 }, "NW", 1, 2, 5, true }
+        }, win_viewport={
+          [2] = {win = {id = 1000}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 1, sum_scroll_delta = 0};
+          [4] = {win = {id = 1001}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 2, sum_scroll_delta = 0};
+        }}
+      else
+        screen:expect{grid=[[
+          ^                                        |
+          {0:~                                       }|
+          {0:~    }{5:╔═════════╗}{0:                        }|
+          {0:~    }{5:║}{1: halloj! }{5:║}{0:                        }|
+          {0:~    }{5:║}{1: BORDAA  }{5:║}{0:                        }|
+          {0:~    }{5:╚═════}🦄BB{5:╝}{0:                        }|
+                                                  |
+        ]]}
+      end
+    end)
+
+    it('border with title and footer', function()
+      local buf = meths.create_buf(false, false)
+      meths.buf_set_lines(buf, 0, -1, true, {' halloj! ',
+                                             ' BORDAA  '})
+      local win = meths.open_win(buf, false, {
+        relative='editor', width=9, height=2, row=2, col=5, border="double",
+        title = "Left", title_pos = "left", footer = "Right", footer_pos = "right",
+      })
+
+      if multigrid then
+        screen:expect{grid=[[
+        ## grid 1
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [3:----------------------------------------]|
+        ## grid 2
+          ^                                        |
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+        ## grid 3
+                                                  |
+        ## grid 4
+          {5:╔}{11:Left}{5:═════╗}|
+          {5:║}{1: halloj! }{5:║}|
+          {5:║}{1: BORDAA  }{5:║}|
+          {5:╚════}{11:Right}{5:╝}|
+        ]], float_pos={
+          [4] = { { id = 1001 }, "NW", 1, 2, 5, true }
+        }, win_viewport={
+          [2] = {win = {id = 1000}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 1, sum_scroll_delta = 0};
+          [4] = {win = {id = 1001}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 2, sum_scroll_delta = 0};
+        }}
+      else
+        screen:expect{grid=[[
+          ^                                        |
+          {0:~                                       }|
+          {0:~    }{5:╔}{11:Left}{5:═════╗}{0:                        }|
+          {0:~    }{5:║}{1: halloj! }{5:║}{0:                        }|
+          {0:~    }{5:║}{1: BORDAA  }{5:║}{0:                        }|
+          {0:~    }{5:╚════}{11:Right}{5:╝}{0:                        }|
+                                                  |
+        ]]}
+      end
+
+      meths.win_set_config(win, {title= "Center",title_pos="center",footer= "Center",footer_pos="center"})
+      if multigrid then
+        screen:expect{grid=[[
+        ## grid 1
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [3:----------------------------------------]|
+        ## grid 2
+          ^                                        |
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+        ## grid 3
+                                                  |
+        ## grid 4
+          {5:╔═}{11:Center}{5:══╗}|
+          {5:║}{1: halloj! }{5:║}|
+          {5:║}{1: BORDAA  }{5:║}|
+          {5:╚═}{11:Center}{5:══╝}|
+        ]], float_pos={
+          [4] = { { id = 1001 }, "NW", 1, 2, 5, true }
+        }, win_viewport={
+          [2] = {win = {id = 1000}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 1, sum_scroll_delta = 0};
+          [4] = {win = {id = 1001}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 2, sum_scroll_delta = 0};
+        }}
+      else
+        screen:expect{grid=[[
+          ^                                        |
+          {0:~                                       }|
+          {0:~    }{5:╔═}{11:Center}{5:══╗}{0:                        }|
+          {0:~    }{5:║}{1: halloj! }{5:║}{0:                        }|
+          {0:~    }{5:║}{1: BORDAA  }{5:║}{0:                        }|
+          {0:~    }{5:╚═}{11:Center}{5:══╝}{0:                        }|
+                                                  |
+        ]]}
+      end
+
+      meths.win_set_config(win, {title= "Right",title_pos="right",footer= "Left",footer_pos="left"})
+      if multigrid then
+        screen:expect{grid=[[
+        ## grid 1
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [3:----------------------------------------]|
+        ## grid 2
+          ^                                        |
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+        ## grid 3
+                                                  |
+        ## grid 4
+          {5:╔════}{11:Right}{5:╗}|
+          {5:║}{1: halloj! }{5:║}|
+          {5:║}{1: BORDAA  }{5:║}|
+          {5:╚}{11:Left}{5:═════╝}|
+        ]], float_pos={
+          [4] = { { id = 1001 }, "NW", 1, 2, 5, true }
+        }, win_viewport={
+          [2] = {win = {id = 1000}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 1, sum_scroll_delta = 0};
+          [4] = {win = {id = 1001}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 2, sum_scroll_delta = 0};
+        }}
+      else
+        screen:expect{grid=[[
+          ^                                        |
+          {0:~                                       }|
+          {0:~    }{5:╔════}{11:Right}{5:╗}{0:                        }|
+          {0:~    }{5:║}{1: halloj! }{5:║}{0:                        }|
+          {0:~    }{5:║}{1: BORDAA  }{5:║}{0:                        }|
+          {0:~    }{5:╚}{11:Left}{5:═════╝}{0:                        }|
+                                                  |
+        ]]}
+      end
+
+      meths.win_set_config(win, {title= { {"🦄"},{"BB"}},title_pos="right",footer= { {"🦄"},{"BB"}},footer_pos="right"})
+      if multigrid then
+        screen:expect{grid=[[
+        ## grid 1
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [2:----------------------------------------]|
+          [3:----------------------------------------]|
+        ## grid 2
+          ^                                        |
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+          {0:~                                       }|
+        ## grid 3
+                                                  |
+        ## grid 4
+          {5:╔═════}🦄BB{5:╗}|
+          {5:║}{1: halloj! }{5:║}|
+          {5:║}{1: BORDAA  }{5:║}|
+          {5:╚═════}🦄BB{5:╝}|
+        ]], float_pos={
+          [4] = { { id = 1001 }, "NW", 1, 2, 5, true }
+        }, win_viewport={
+          [2] = {win = {id = 1000}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 1, sum_scroll_delta = 0};
+          [4] = {win = {id = 1001}, topline = 0, botline = 2, curline = 0, curcol = 0, linecount = 2, sum_scroll_delta = 0};
+        }}
+      else
+        screen:expect{grid=[[
+          ^                                        |
+          {0:~                                       }|
+          {0:~    }{5:╔═════}🦄BB{5:╗}{0:                        }|
+          {0:~    }{5:║}{1: halloj! }{5:║}{0:                        }|
+          {0:~    }{5:║}{1: BORDAA  }{5:║}{0:                        }|
+          {0:~    }{5:╚═════}🦄BB{5:╝}{0:                        }|
+                                                  |
+        ]]}
+      end
+    end)
+
     it('terminates border on edge of viewport when window extends past viewport', function()
       local buf = meths.create_buf(false, false)
       meths.open_win(buf, false, {relative='editor', width=40, height=7, row=0, col=0, border="single", zindex=201})