local fn = vim.fn

-- boostrap packer
local install_path = fn.stdpath('data') .. '/site/pack/packer/opt/packer.nvim'
local packer_bootstrap
if fn.empty(fn.glob(install_path)) > 0 then
    packer_bootstrap = fn.system({
        'git', 'clone', 'https://github.com/wbthomason/packer.nvim',
        install_path
    })
end

-- run PackerSync everytime plugins.lua is updated
vim.cmd([[
  augroup packer_user_config
    autocmd!
    autocmd BufWritePost plugins.lua source <afile> | PackerSync
  augroup end
]])

vim.cmd([[packadd packer.nvim]])

-- initialize plugins
return require('packer').startup(function(use)
    -- let packer manage itself
    use({'wbthomason/packer.nvim', opt = true})

    -- theme
    use("ishan9299/nvim-solarized-lua")

    -- commenting
    use {
        'numToStr/Comment.nvim',
        config = function() require('Comment').setup() end
    }

    -- session handling
    use('tpope/vim-obsession')
    use('dhruvasagar/vim-prosession')

    -- tabline
    use {
        'kdheepak/tabline.nvim',
        config = function()
            require'tabline'.setup {
                enable = true,
                options = {show_bufnr = true, show_filename_only = true}
            }
        end,
        requires = {
            {'hoob3rt/lualine.nvim'},
            {'kyazdani42/nvim-web-devicons', opt = true}
        }
    }

    -- status line
    use {
        'nvim-lualine/lualine.nvim',
        requires = {'kyazdani42/nvim-web-devicons', opt = true},
        config = function() require('lualine').setup() end
    }

    -- blankline
    use({
        "lukas-reineke/indent-blankline.nvim",
        config = function()
            require("indent_blankline").setup {
                char = "┊",
                buftype_exclude = {"terminal", "help", "nofile"},
                filetype_exclude = {'help', 'packer'},
                show_trailing_blankline_indent = false
            }
        end
    })

    -- git
    use('tpope/vim-fugitive')
    use({
        'lewis6991/gitsigns.nvim',
        requires = {'nvim-lua/plenary.nvim'},
        config = function() require('gitsigns').setup() end
    })
    use("junegunn/gv.vim")

    -- autocompletion
    use({
        "L3MON4D3/LuaSnip",
        requires = {"rafamadriz/friendly-snippets"},
        config = function()
            require("luasnip.loaders.from_vscode").lazy_load()
        end
    })
    use({
        "hrsh7th/nvim-cmp",
        requires = {
            "hrsh7th/cmp-nvim-lsp", "hrsh7th/cmp-buffer", "hrsh7th/cmp-path",
            "hrsh7th/cmp-cmdline", "hrsh7th/cmp-git", "hrsh7th/cmp-nvim-lua",
            "saadparwaiz1/cmp_luasnip", "hrsh7th/cmp-nvim-lsp-signature-help",
            "davidsierradz/cmp-conventionalcommits", "hrsh7th/cmp-nvim-lua",
            "hrsh7th/cmp-calc"
        },
        config = function()
            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 cmp = require('cmp')
            local luasnip = require("luasnip")

            cmp.setup({
                snippet = {
                    expand = function(args)
                        require("luasnip").lsp_expand(args.body)
                    end
                },
                sources = require("cmp").config.sources({
                    {name = "nvim_lsp"}, {name = "luasnip"}, {name = "path"},
                    {name = "buffer"}, {name = "git"},
                    {name = 'nvim_lsp_signature_help'},
                    {name = "conventionalcommits"}, {name = "nvim-lua"},
                    {name = "calc"}
                }),
                mapping = {
                    ['<C-Space>'] = cmp.mapping(cmp.mapping.complete(),
                                                {'i', 'c'}),
                    ['<CR>'] = cmp.mapping.confirm({select = true}),
                    ["<Tab>"] = cmp.mapping(function(fallback)
                        if cmp.visible() then
                            cmp.select_next_item()
                        elseif luasnip.expand_or_jumpable() then
                            luasnip.expand_or_jump()
                        elseif has_words_before() then
                            cmp.complete()
                        else
                            fallback()
                        end
                    end, {"i", "s"}),

                    ["<S-Tab>"] = cmp.mapping(function(fallback)
                        if cmp.visible() then
                            cmp.select_prev_item()
                        elseif luasnip.jumpable(-1) then
                            luasnip.jump(-1)
                        else
                            fallback()
                        end
                    end, {"i", "s"})
                },
                experimental = {ghost_text = true}
            })

            -- `/` cmdline setup.
            cmp.setup.cmdline('/', {sources = {{name = 'buffer'}}})

            -- `:` cmdline setup.
            cmp.setup.cmdline(':', {
                sources = cmp.config
                    .sources({{name = 'path'}}, {{name = 'cmdline'}})
            })

        end
    })

    -- highlight current symbol
    use({"RRethy/vim-illuminate"})

    -- language server
    use({
        "neovim/nvim-lspconfig",
        config = function() require("plugins.lspconfig") end
    })

    use('williamboman/nvim-lsp-installer')

    -- treesitter
    use({
        'nvim-treesitter/nvim-treesitter',
        config = function() require('plugins.treesitter') end,
        run = ':TSUpdate'
    })

    -- Telescope
    use({
        'nvim-telescope/telescope.nvim',
        requires = {{'nvim-lua/plenary.nvim'}},
        config = function() require('plugins.telescope') end
    })
    use({'nvim-telescope/telescope-fzf-native.nvim', run = 'make'})

    -- automatic pairs
    use({"Raimondi/delimitMate"})

    -- markdown preview
    use({'iamcco/markdown-preview.nvim'})

    -- terminal
    use({
        "akinsho/nvim-toggleterm.lua",
        config = function()
            require("toggleterm").setup({size = 32, open_mapping = [[<F4>]]})
        end
    })

    -- buffer closing
    use({"sar/bbye.nvim"})

    -- ansible filetype
    use({"pearofducks/ansible-vim"})

    if packer_bootstrap then require('packer').sync() end
end)