dotfiles/.config/nvim/lua/statusline.lua

-- Author        : swytch
-- Created       : Friday Mar 12, 2021 21:45:21 CET
-- License       : GPLv3
-- Description   : neovim statusline file
--                 based on github/nihilistkitten's work


local function gen_section(hl_string, items)
    local out = ""
    for _, item in pairs(items) do
        if item ~= "" then
            out = out .. " " .. item
        end
    end
    if out ~="" then
        return hl_string .. out .. " "
    else
        return out
    end
end

-- sensible names for vim modes
local function get_mode(m)
    local mode_group = {
        ["n"]           = "Normal",
        ["no"]          = "O-Pending",
        ["nov"]         = "O-Pending",
        ["noV"]         = "O-Pending",
        ["no"]        = "O-Pending",
        ["niI"]         = "Normal",
        ["niR"]         = "Normal",
        ["niV"]         = "Normal",
        ["v"]           = "Visual",
        ["V"]           = "V-Line",
        [""]          = "V-Block",
        ["s"]           = "Select",
        ["S"]           = "S-Line",
        [""]          = "S-Block",
        ["i"]           = "Insert",
        ["ic"]          = "Insert",
        ["ix"]          = "Insert",
        ["R"]           = "Replace",
        ["Rc"]          = "Replace",
        ["Rv"]          = "V-Replace",
        ["Rx"]          = "Replace",
        ["c"]           = "Command",
        ["cv"]          = "Ex",
        ["ce"]          = "Ex",
        ["r"]           = "Prompt",
        ["rm"]          = "Prompt",
        ["r?"]          = "Prompt",
        ["!"]           = "Shell",
        ["t"]           = "Terminal",
    }
    return mode_group[m] or "None"
end

local function get_mode_display_name(m)
    local mode = {
        ["Normal"]      = "[ NRM ]",
        ["O-Pending"]   = "[ OTR ]",
        ["Visual"]      = "[ VSL ]",
        ["V-Line"]      = "[ V·L ]",
        ["V-Block"]     = "[ V·B ]",
        ["Select"]      = "[ SEL ]",
        ["S-Line"]      = "[ S·L ]",
        ["S-Block"]     = "[ S·B ]",
        ["Insert"]      = "[ INS ]",
        ["Replace"]     = "[ RPL ]",
        ["Command"]     = "[ CMD ]",
        ["Prompt"]      = "[ PMT ]",
        ["Shell"]       = "[ SHL ]",
        ["Terminal"]    = "[ TRM ]",
        ["None"]        = "[ --- ]"
    }
    return mode[m]
end

-- get the highlight group for a mode group
local function get_mode_color(m)
    local color = {
        ["Normal"]      = "%#NormalMode#",
        ["O-Pending"]   = "%#NormalMode#",
        ["Visual"]      = "%#VisualMode#",
        ["V-Line"]      = "%#VisualMode#",
        ["V-Block"]     = "%#VisualMode#",
        ["Select"]      = "%#NormalMode#",
        ["S-Line"]      = "%#NormalMode#",
        ["S-Block"]     = "%#NormalMode#",
        ["Insert"]      = "%#InsertMode#",
        ["Replace"]     = "%#ReplaceMode#",
        ["Command"]     = "%#CommandMode#",
        ["Prompt"]      = "%#NormalMode#",
        ["Shell"]       = "%#NormalMode#",
        ["Terminal"]    = "%#NormalMode#",
        ["None"]        = "%#NormalMode#"
    }
    return color[m]
end

-- from https://github.com/nvim-lua/lsp-status.nvim/blob/master/lua/lsp-status/diagnostics.lua
local function get_lsp_diagnostics(bufnr)
    local result = {}
    local levels = {
        errors = "Error",
        warnings = "Warn",
        info = "Info",
        hints = "Hint"
    }

    for k, level in pairs(levels) do
        local count = 0
        local diags = vim.diagnostic.get(bufnr, { severity = level })
        for _, _ in pairs(diags) do
            count = count + 1
        end
        result[k] = count
    end

    return result
end

local function process_diagnostics(prefix, n, hl)
if n > 0 then
    return hl .. prefix .. n
else
    return ""
end
end

local function spell_check()
if vim.wo.spell then
    local lang = vim.o.spelllang
    return "[SPELL=" .. lang .. "]"
else
    return ""
end
end

local function statusline_focused()
local diagnostics = get_lsp_diagnostics()
local mode = vim.fn.mode()
local mg = get_mode(mode)
local accent_color = get_mode_color(mg)

local left = table.concat {
    gen_section(accent_color, {get_mode_display_name(mg)}),
    gen_section("%#Middle#", {"%f"}),
    gen_section("%#Bottom#", {"%m", "%r"}),
    gen_section(
        "%#Alert#",
        {
            process_diagnostics(
                globals.sign_error .. " ",
                diagnostics.errors,
                "%#DiagnosticVirtualTextError#"
            ),
            process_diagnostics(
                globals.sign_warning .. " ",
                diagnostics.warnings,
                "%#DiagnosticVirtualTextWarn#"
            ),
            process_diagnostics(
                globals.sign_info .. " ",
                diagnostics.info,
                "%#DiagnosticVirtualTextInfo#"
            )
        }
    )
}
local right = table.concat {
    gen_section(
        "%#Bottom#",
        {
            spell_check(),
            vim.bo.filetype
        }
    ),
    gen_section("%#Middle#", {"%03.p%%"}),
    gen_section("%#Top#", {"-%03.c-"})
}

return table.concat {
    left,
    "%#Statusline#",
    "%=",
    right
}

end

local function statusline_not_focused()
    return table.concat {
        gen_section("%#StatuslineNF#", {"%f", "%m"}),
        "%=",
        gen_section("%#StatuslineNF#", {"%03.p%%"}),
        gen_section("%#StatuslineNF#", {"-%03.c-"})
    }
end

function _G.gen_statusline()
    if vim.g.statusline_winid == vim.fn.win_getid() then
        return statusline_focused()
    else
        return statusline_not_focused()
    end
end

vim.o.statusline = "%!luaeval(\"gen_statusline()\")"