local cmp = require("cmp")
local luasnip = require("luasnip")

local has_words_before = function()
    local line, col = unpack(vim.api.nvim_win_get_cursor(0))
    return col ~= 0 and vim.api.nvim_buf_get_lines(0, line - 1, line, true)[1]:sub(col, col):match("%s") == nil
end

local has_copilot = function()
    if vim.api.nvim_get_option_value("buftype", {}) == "prompt" then
        return false
    end
    local line, col = unpack(vim.api.nvim_win_get_cursor(0))
    return col ~= 0 and vim.api.nvim_buf_get_text(0, line - 1, 0, line - 1, col, {})[1]:match("^%s*$") == nil
end

local M = {}

M.tab = function(fallback)
    if cmp.visible() then
        cmp.select_next_item(has_copilot() and { behavior = cmp.SelectBehavior.Select } or {})
        return
    end

    if luasnip.expand_or_jumpable() then
        luasnip.expand_or_jump()
        return
    end

    if has_words_before() then
        cmp.complete()
        return
    end

    fallback()
end

M.shift_tab = function(fallback)
    if cmp.visible() then
        cmp.select_prev_item()
        return
    end

    if luasnip.jumpable(-1) then
        luasnip.jump(-1)
        return
    end

    fallback()
end

return M