feat(git): add blame side window with synced scroll

lua/core/keymap.lua

@@ -235,6 +235,7 @@ vim.keymap.set("n", "<leader>gc", "<Plug>(git-commit)")
 vim.keymap.set("n", "<leader>ga", "<Plug>(git-commit-amend)")
 vim.keymap.set("n", "<leader>gl", "<Plug>(git-log)")
 vim.keymap.set("n", "<leader>gb", "<Plug>(git-blame-popup)")
+vim.keymap.set("n", "<leader>gB", "<Plug>(git-blame-view)")
 vim.keymap.set("n", "<leader>gv", "<Plug>(git-hunk-select)")
 vim.keymap.set("n", "<leader>gs", "<Plug>(git-hunk-stage-toggle)")
 vim.keymap.set("n", "<leader>gr", "<Plug>(git-hunk-reset)")

lua/git/blame.lua

@@ -6,8 +6,14 @@ local M = {}
 
 local NS_INLINE = vim.api.nvim_create_namespace("ow.git.blame.inline")
 local NS_POPUP = vim.api.nvim_create_namespace("ow.git.blame.popup")
+local NS_VIEW = vim.api.nvim_create_namespace("ow.git.blame.view")
 
 local ZERO_SHA = string.rep("0", 40)
+local SHA_W = 8
+local AUTHOR_W = 20
+local DATE_W = 10
+local GAP = "  "
+local VIEW_WIDTH = SHA_W + #GAP + AUTHOR_W + #GAP + DATE_W
 
 ---@class ow.Git.Blame.Commit
 ---@field sha string
@@ -441,6 +447,207 @@ function M.toggle_inline(buf)
     end
 end
 
+---@class ow.Git.Blame.View
+---@field source_buf integer
+---@field source_win integer
+---@field view_buf integer
+---@field view_win integer
+---@field group integer
+
+---@type table<integer, ow.Git.Blame.View>
+local views = {}
+
+---@param s string
+---@param w integer
+---@return string
+local function pad_w(s, w)
+    local sw = vim.api.nvim_strwidth(s)
+    if sw > w then
+        return vim.fn.strcharpart(s, 0, w)
+    end
+    return s .. string.rep(" ", w - sw)
+end
+
+---@param state ow.Git.Blame.BufState
+---@param line_count integer
+---@return string[]
+local function build_view_lines(state, line_count)
+    local lines = {}
+    for lnum = 1, line_count do
+        local sha = state.line_sha[lnum]
+        local commit = sha and state.commits[sha]
+        if commit and not util.is_zero_sha(sha) then
+            local author = pad_w(commit.author, AUTHOR_W)
+            local date = os.date("%Y-%m-%d", commit.author_time)
+            lines[lnum] = sha:sub(1, SHA_W) .. GAP .. author .. GAP .. date
+        else
+            lines[lnum] = pad_w("Uncommitted", VIEW_WIDTH)
+        end
+    end
+    return lines
+end
+
+---@param view ow.Git.Blame.View
+---@param state ow.Git.Blame.BufState
+local function render_view(view, state)
+    if not vim.api.nvim_buf_is_valid(view.view_buf) then
+        return
+    end
+    local line_count = vim.api.nvim_buf_line_count(view.source_buf)
+    local lines = build_view_lines(state, line_count)
+    util.set_buf_lines(view.view_buf, 0, -1, lines)
+    vim.api.nvim_buf_clear_namespace(view.view_buf, NS_VIEW, 0, -1)
+    local author_col = SHA_W + #GAP
+    local date_col = author_col + AUTHOR_W + #GAP
+    for lnum = 1, #lines do
+        local sha = state.line_sha[lnum]
+        if sha and not util.is_zero_sha(sha) then
+            pcall(vim.api.nvim_buf_set_extmark, view.view_buf, NS_VIEW, lnum - 1, 0, {
+                end_col = SHA_W,
+                hl_group = "GitBlameSha",
+            })
+            pcall(vim.api.nvim_buf_set_extmark, view.view_buf, NS_VIEW, lnum - 1, author_col, {
+                end_col = author_col + AUTHOR_W,
+                hl_group = "GitBlameAuthor",
+            })
+            pcall(vim.api.nvim_buf_set_extmark, view.view_buf, NS_VIEW, lnum - 1, date_col, {
+                end_col = date_col + DATE_W,
+                hl_group = "GitBlameDate",
+            })
+        end
+    end
+end
+
+---@param source_buf integer
+local function close_view(source_buf)
+    local view = views[source_buf]
+    if not view then
+        return
+    end
+    views[source_buf] = nil
+    pcall(vim.api.nvim_del_augroup_by_id, view.group)
+    if vim.api.nvim_win_is_valid(view.source_win) then
+        vim.wo[view.source_win].scrollbind = false
+        vim.wo[view.source_win].cursorbind = false
+    end
+    if vim.api.nvim_win_is_valid(view.view_win) then
+        pcall(vim.api.nvim_win_close, view.view_win, true)
+    end
+end
+
+---@param source_buf integer
+---@param state ow.Git.Blame.BufState
+---@param source_win integer
+local function open_view(source_buf, state, source_win)
+    local view_buf = vim.api.nvim_create_buf(false, true)
+    util.setup_scratch(view_buf, { buftype = "nofile", bufhidden = "wipe" })
+    vim.bo[view_buf].filetype = "gitblame"
+    local view_win = vim.api.nvim_open_win(view_buf, false, {
+        split = "left",
+        width = VIEW_WIDTH,
+        win = source_win,
+    })
+    vim.api.nvim_set_option_value("number", false, { win = view_win, scope = "local" })
+    vim.api.nvim_set_option_value("relativenumber", false, { win = view_win, scope = "local" })
+    vim.api.nvim_set_option_value("signcolumn", "no", { win = view_win, scope = "local" })
+    vim.api.nvim_set_option_value("foldcolumn", "0", { win = view_win, scope = "local" })
+    vim.api.nvim_set_option_value("wrap", false, { win = view_win, scope = "local" })
+    vim.api.nvim_set_option_value("cursorline", true, { win = view_win, scope = "local" })
+    vim.api.nvim_set_option_value("winfixwidth", true, { win = view_win, scope = "local" })
+    vim.api.nvim_set_option_value("statuscolumn", "", { win = view_win, scope = "local" })
+
+    if not vim.tbl_contains(vim.opt.scrollopt:get(), "ver") then
+        vim.opt.scrollopt:append("ver")
+    end
+    vim.wo[source_win].scrollbind = true
+    vim.wo[source_win].cursorbind = true
+    vim.wo[view_win].scrollbind = true
+    vim.wo[view_win].cursorbind = true
+
+    local group = vim.api.nvim_create_augroup(
+        "ow.git.blame.view." .. source_buf,
+        { clear = true }
+    )
+
+    ---@type ow.Git.Blame.View
+    local view = {
+        source_buf = source_buf,
+        source_win = source_win,
+        view_buf = view_buf,
+        view_win = view_win,
+        group = group,
+    }
+    views[source_buf] = view
+    render_view(view, state)
+    vim.api.nvim_win_call(view_win, function()
+        vim.cmd("syncbind")
+    end)
+
+    vim.api.nvim_create_autocmd("WinClosed", {
+        group = group,
+        callback = function(args)
+            local closed = tonumber(args.match)
+            if closed == view_win or closed == source_win then
+                vim.schedule(function()
+                    close_view(source_buf)
+                end)
+            end
+        end,
+    })
+    vim.api.nvim_create_autocmd({ "BufWipeout", "BufDelete" }, {
+        group = group,
+        buffer = view_buf,
+        callback = function()
+            vim.schedule(function()
+                close_view(source_buf)
+            end)
+        end,
+    })
+
+    vim.keymap.set("n", "<CR>", function()
+        local lnum = vim.api.nvim_win_get_cursor(view_win)[1]
+        local sha = state.line_sha[lnum]
+        if not sha or util.is_zero_sha(sha) then
+            util.warning("git blame: line is not committed yet")
+            return
+        end
+        object.open(state.repo, sha, { split = false })
+    end, { buffer = view_buf, silent = true, desc = "Open the commit" })
+    vim.keymap.set("n", "q", function()
+        close_view(source_buf)
+    end, { buffer = view_buf, silent = true, desc = "Close the blame view" })
+end
+
+---@param buf integer?
+function M.toggle_view(buf)
+    buf = resolve_buf(buf)
+    if views[buf] then
+        close_view(buf)
+        return
+    end
+    local state = ensure_state(buf)
+    if not state then
+        util.warning("git blame: nothing to blame in this buffer")
+        return
+    end
+    local source_win = vim.api.nvim_get_current_win()
+    if vim.api.nvim_win_get_buf(source_win) ~= buf then
+        source_win = vim.fn.bufwinid(buf)
+    end
+    if source_win == -1 then
+        return
+    end
+    run_blame(state, buf, function()
+        if
+            not vim.api.nvim_buf_is_valid(buf)
+            or not vim.api.nvim_win_is_valid(source_win)
+        then
+            return
+        end
+        open_view(buf, state, source_win)
+    end)
+end
+
 ---@param lines string[]
 ---@return integer width
 ---@return integer height
@@ -677,6 +884,7 @@ end
 
 ---@param buf integer
 function M.detach(buf)
+    close_view(buf)
     local state = states[buf]
     if not state then
         return

plugin/git.lua

@@ -322,6 +322,9 @@ vim.api.nvim_create_user_command("GitDiffOverlay", function()
     require("git.hunks").toggle_overlay()
 end, { desc = "Toggle the git diff overlay in the current buffer" })
 
+vim.keymap.set("n", "<Plug>(git-blame-view)", function()
+    require("git.blame").toggle_view()
+end, { silent = true, desc = "Toggle the git blame side window" })
 vim.keymap.set("n", "<Plug>(git-blame-line)", function()
     require("git.blame").toggle_inline()
 end, { silent = true, desc = "Toggle inline git blame" })
@@ -341,6 +344,9 @@ end, {
     desc = "Open this file at the parent of the line's commit",
 })
 
+vim.api.nvim_create_user_command("GitBlame", function()
+    require("git.blame").toggle_view()
+end, { desc = "Toggle the git blame side window" })
 vim.api.nvim_create_user_command("GitBlameLine", function()
     require("git.blame").toggle_inline()
 end, { desc = "Toggle inline git blame in the current buffer" })

test/git/blame_test.lua

@@ -197,6 +197,7 @@ t.test("blame actions are no-ops off a worktree", function()
     t.quietly(function()
         blame.line_popup(buf)
         blame.toggle_inline(buf)
+        blame.toggle_view(buf)
     end)
     t.eq(blame.state(buf), nil, "no state created for a non-worktree buffer")
 end)
@@ -300,6 +301,99 @@ t.test("inline annotation follows the cursor", function()
     t.eq(assert(inline_marks(buf)[1])[2], 2, "annotation moved to line 3")
 end)
 
+---@param buf integer
+---@return integer view_win
+local function wait_view(buf)
+    local win ---@type integer?
+    t.wait_for(function()
+        for _, w in ipairs(vim.api.nvim_list_wins()) do
+            local b = vim.api.nvim_win_get_buf(w)
+            if b ~= buf and vim.bo[b].filetype == "gitblame" then
+                win = w
+                return true
+            end
+        end
+        return false
+    end, "the blame side window to open")
+    return (assert(win))
+end
+
+t.test("toggle_view opens and closes a side split", function()
+    local _, buf = setup("alpha\nbeta\ngamma\n")
+    vim.api.nvim_set_current_buf(buf)
+    blame.toggle_view(buf)
+    local view_win = wait_view(buf)
+    t.defer(function()
+        if vim.api.nvim_win_is_valid(view_win) then
+            vim.api.nvim_win_close(view_win, true)
+        end
+    end)
+    blame.toggle_view(buf)
+    t.falsy(
+        vim.api.nvim_win_is_valid(view_win),
+        "toggling again closes the view"
+    )
+end)
+
+t.test("the side view shows sha, author and an absolute date", function()
+    local dir, buf = setup("alpha\nbeta\ngamma\n")
+    local sha = h.git(dir, "rev-parse", "HEAD").stdout
+    vim.api.nvim_set_current_buf(buf)
+    blame.toggle_view(buf)
+    local view_win = wait_view(buf)
+    t.defer(function()
+        if vim.api.nvim_win_is_valid(view_win) then
+            vim.api.nvim_win_close(view_win, true)
+        end
+    end)
+    local view_buf = vim.api.nvim_win_get_buf(view_win)
+    local row = vim.api.nvim_buf_get_lines(view_buf, 0, 1, false)[1] or ""
+    t.truthy(
+        vim.startswith(row, sha:sub(1, 8)),
+        "the row starts with the short sha"
+    )
+    t.truthy(row:find("t", 1, true), "the row includes the author")
+    t.truthy(
+        row:match("%d%d%d%d%-%d%d%-%d%d$"),
+        "the row ends with a YYYY-MM-DD date"
+    )
+end)
+
+t.test("<CR> on the view row opens the commit", function()
+    local _, buf = setup("alpha\nbeta\ngamma\n")
+    vim.api.nvim_set_current_buf(buf)
+    blame.toggle_view(buf)
+    local view_win = wait_view(buf)
+    t.defer(function()
+        if vim.api.nvim_win_is_valid(view_win) then
+            vim.api.nvim_win_close(view_win, true)
+        end
+    end)
+    vim.api.nvim_set_current_win(view_win)
+    vim.api.nvim_win_set_cursor(view_win, { 1, 0 })
+    t.press("<CR>")
+    wait_buf_name("^git://%x+$")
+end)
+
+t.test("closing the source window tears down the view", function()
+    local _, buf = setup("alpha\nbeta\ngamma\n")
+    vim.api.nvim_set_current_buf(buf)
+    local source_win = vim.api.nvim_get_current_win()
+    vim.cmd("split")
+    vim.api.nvim_set_current_win(source_win)
+    blame.toggle_view(buf)
+    local view_win = wait_view(buf)
+    t.defer(function()
+        if vim.api.nvim_win_is_valid(view_win) then
+            vim.api.nvim_win_close(view_win, true)
+        end
+    end)
+    vim.api.nvim_win_close(source_win, true)
+    t.wait_for(function()
+        return not vim.api.nvim_win_is_valid(view_win)
+    end, "the view to close when the source window closes")
+end)
+
 t.test("open_commit opens the commit that last touched the line", function()
     local _, buf = setup("alpha\nbeta\ngamma\n")
     vim.api.nvim_set_current_buf(buf)