feat(git): replace vim-fugitive with custom git module

lua/git/diff.lua

@@ -0,0 +1,179 @@
+local log = require("log")
+local repo = require("git.repo")
+
+local M = {}
+
+---@param buf integer
+---@param worktree string
+---@param path string
+local function attach_index_writer(buf, worktree, path)
+    vim.api.nvim_create_autocmd("BufWriteCmd", {
+        buffer = buf,
+        callback = function()
+            local body = table.concat(
+                vim.api.nvim_buf_get_lines(buf, 0, -1, false),
+                "\n"
+            ) .. "\n"
+            local hash = vim.system(
+                { "git", "hash-object", "-w", "--stdin" },
+                { cwd = worktree, stdin = body, text = true }
+            ):wait()
+            if hash.code ~= 0 then
+                log.error("git hash-object failed: %s", hash.stderr or "")
+                return
+            end
+            local sha = vim.trim(hash.stdout or "")
+            local mode = "100644"
+            local ls = vim.system(
+                { "git", "ls-files", "-s", "--", path },
+                { cwd = worktree, text = true }
+            ):wait()
+            if ls.code == 0 and ls.stdout then
+                local m = ls.stdout:match("^(%d+)")
+                if m then
+                    mode = m
+                end
+            end
+            local upd = vim.system({
+                "git",
+                "update-index",
+                "--cacheinfo",
+                mode .. "," .. sha .. "," .. path,
+            }, { cwd = worktree, text = true }):wait()
+            if upd.code ~= 0 then
+                log.error("git update-index failed: %s", upd.stderr or "")
+                return
+            end
+            vim.bo[buf].modified = false
+        end,
+    })
+end
+
+---@param worktree string
+---@param revspec string  anything `git show` accepts (e.g. `HEAD:foo`, `:foo`, blob SHA)
+---@return string[]
+local function read_show(worktree, revspec)
+    local result = vim.system(
+        { "git", "show", revspec },
+        { cwd = worktree, text = true }
+    )
+        :wait()
+    local content = result.code == 0 and (result.stdout or "") or ""
+    local lines = vim.split(content, "\n", { plain = true, trimempty = false })
+    if #lines > 0 and lines[#lines] == "" then
+        table.remove(lines)
+    end
+    return lines
+end
+
+---@param worktree string
+---@param ref string '' for index, 'HEAD' or a sha for committed refs
+---@param path string
+---@param is_index boolean? true to hook :w to update the git index
+---@return integer
+function M.git_show_buf(worktree, ref, path, is_index)
+    local lines = read_show(worktree, ref .. ":" .. path)
+    local buf = vim.api.nvim_create_buf(false, true)
+    vim.api.nvim_buf_set_lines(buf, 0, -1, false, lines)
+    vim.bo[buf].buftype = is_index and "acwrite" or "nofile"
+    vim.bo[buf].bufhidden = "wipe"
+    vim.bo[buf].swapfile = false
+    if not is_index then
+        vim.bo[buf].modifiable = false
+    end
+    if is_index then
+        attach_index_writer(buf, worktree, path)
+    end
+    vim.bo[buf].modified = false
+    return buf
+end
+
+---@param worktree string
+---@param blob string  the blob SHA (full or abbreviated)
+---@return integer
+function M.git_show_blob(worktree, blob)
+    local lines = read_show(worktree, blob)
+    local buf = vim.api.nvim_create_buf(false, true)
+    vim.api.nvim_buf_set_lines(buf, 0, -1, false, lines)
+    vim.bo[buf].buftype = "nofile"
+    vim.bo[buf].bufhidden = "wipe"
+    vim.bo[buf].swapfile = false
+    vim.bo[buf].modifiable = false
+    vim.bo[buf].modified = false
+    return buf
+end
+
+---@return integer
+function M.empty_buf()
+    local buf = vim.api.nvim_create_buf(false, true)
+    vim.bo[buf].buftype = "nofile"
+    vim.bo[buf].bufhidden = "wipe"
+    vim.bo[buf].swapfile = false
+    vim.bo[buf].modifiable = false
+    vim.bo[buf].modified = false
+    return buf
+end
+
+---@param abs_path string
+---@return integer
+function M.load_file_buf(abs_path)
+    for _, buf in ipairs(vim.api.nvim_list_bufs()) do
+        if
+            vim.api.nvim_buf_is_loaded(buf)
+            and vim.api.nvim_buf_get_name(buf) == abs_path
+        then
+            return buf
+        end
+    end
+    local buf = vim.fn.bufadd(abs_path)
+    vim.fn.bufload(buf)
+    return buf
+end
+
+---@param buf integer
+---@param name string
+local function set_buf_name_and_filetype(buf, name)
+    pcall(vim.api.nvim_buf_set_name, buf, name)
+    local ft = vim.filetype.match({ buf = buf })
+    if ft then
+        vim.bo[buf].filetype = ft
+    end
+end
+
+---@class ow.Git.SplitOpts
+---@field ref string '' for index, 'HEAD' for HEAD
+---@field vertical boolean
+
+---@param opts ow.Git.SplitOpts
+function M.split(opts)
+    local cur_buf = vim.api.nvim_get_current_buf()
+    local cur_path = vim.api.nvim_buf_get_name(cur_buf)
+    if cur_path == "" then
+        log.warning("no file in current buffer")
+        return
+    end
+    local _, worktree = repo.resolve(cur_path)
+    if not worktree then
+        log.warning("not in a git repository")
+        return
+    end
+    local rel = vim.fs.relpath(worktree, cur_path)
+    if not rel then
+        log.warning("file is outside the worktree")
+        return
+    end
+
+    local is_index = opts.ref == ""
+    local other = M.git_show_buf(worktree, opts.ref, rel, is_index)
+    local label = is_index and "index" or opts.ref
+    set_buf_name_and_filetype(other, "git://" .. label .. "/" .. rel)
+
+    local split_cmd = opts.vertical and "leftabove vertical sbuffer "
+        or "leftabove sbuffer "
+    vim.cmd(split_cmd .. other)
+    vim.cmd("diffthis")
+    vim.cmd("wincmd p")
+    vim.cmd("diffthis")
+end
+
+return M