From 53d8012e5e4b2115ade2c15d040223ef97ffb05c Mon Sep 17 00:00:00 2001
From: Folke Lemaitre <folke.lemaitre@gmail.com>
Date: Mon, 3 Nov 2025 21:50:49 +0100
Subject: [PATCH] fix(picker.diff): parse full diff including diff and hunk
 headers. Closes #2429

---
 lua/snacks/picker/format.lua      |   2 +-
 lua/snacks/picker/source/diff.lua | 108 +++++++++++++++++++++++-------
 2 files changed, 83 insertions(+), 27 deletions(-)

diff --git a/lua/snacks/picker/format.lua b/lua/snacks/picker/format.lua
index c9b10477..2f499305 100644
--- a/lua/snacks/picker/format.lua
+++ b/lua/snacks/picker/format.lua
@@ -564,7 +564,7 @@ function M.git_status(item, picker)
   local status = item.status
   if not status and item.block then
     local block = item.block ---@type snacks.picker.diff.Block
-    status = ({ new = "A", delete = "D", rename = "R", copy = "C" })[block.type] or "M"
+    status = block.new and "A" or block.delete and "D" or block.rename and "R" or block.copy and "C" or "M"
     status = block.unmerged and (status .. status) or item.staged and (status .. " ") or (" " .. status)
   elseif not status then
     return M.filename(item, picker)
diff --git a/lua/snacks/picker/source/diff.lua b/lua/snacks/picker/source/diff.lua
index 0b0c1c44..b89bf6ea 100644
--- a/lua/snacks/picker/source/diff.lua
+++ b/lua/snacks/picker/source/diff.lua
@@ -8,15 +8,26 @@ local M = {}
 ---@class snacks.picker.diff.Hunk
 ---@field diff string[]
 ---@field line number
+---@field context? string
+---@field left { line: number, count: number } old (normal) /ours (merge)
+---@field right { line: number, count: number } new (normal) /working (merge)
+---@field parents? { line: number, count: number }[] theirs (merge)
 
 ---@class snacks.picker.diff.Block
----@field type? "new"|"delete"|"rename"|"copy"|"mode"
 ---@field unmerged? boolean
 ---@field file string
 ---@field left? string
 ---@field right? string
 ---@field header string[]
 ---@field hunks snacks.picker.diff.Hunk[]
+---@field mode? {from:string, to:string}
+---@field copy? {from:string, to:string}
+---@field rename? {from:string, to:string}
+---@field delete? string (mode of deleted file)
+---@field new? string (mode of new file)
+---@field similarity? number
+---@field dissimilarity? number
+---@field index? {from:string, to:string, mode:string}
 
 ---@param opts? snacks.picker.diff.Config
 ---@type snacks.picker.finder
@@ -63,7 +74,7 @@ function M.diff(opts, ctx)
         diff = table.concat(diff, "\n"),
         file = file,
         cwd = cwd,
-        rename = block.type == "rename" and block.left or nil,
+        rename = block.rename and block.rename.from or nil,
         block = block,
         pos = { line, 0 },
       })
@@ -94,14 +105,18 @@ function M.parse(lines)
   local ret = {} ---@type snacks.picker.diff.Block[]
 
   ---@param file? string
+  ---@param strip_prefix? boolean
   ---@return string?
-  local function norm(file)
+  local function norm(file, strip_prefix)
     if file then
       file = file:gsub("\t.*$", "") -- remove tab and after
       file = file:gsub('^"(.-)"$', "%1") -- remove quotes
       if file == "/dev/null" then -- no file
         return
       end
+      if strip_prefix == false then
+        return file
+      end
       local prefix = { "a", "b", "i", "w", "c", "o", "old", "new" }
       for _, s in ipairs(prefix) do -- remove prefixes
         if file:sub(1, #s + 1) == s .. "/" then
@@ -124,23 +139,40 @@ function M.parse(lines)
       elseif line:find("^%+%+%+ ") then
         block.right = norm(line:sub(5))
       elseif line:find("^rename from") then
-        block.type = "rename"
-        block.left = norm(line:match("^rename from (.*)"))
+        block.rename = block.rename or {}
+        block.left = norm(line:match("^rename from (.*)"), false)
+        block.rename.from = block.left
       elseif line:find("^rename to") then
-        block.type = "rename"
-        block.right = norm(line:match("^rename to (.*)"))
+        block.rename = block.rename or {}
+        block.right = norm(line:match("^rename to (.*)"), false)
+        block.rename.to = block.right
       elseif line:find("^copy from") then
-        block.type = "copy"
-        block.left = norm(line:match("^copy from (.*)"))
+        block.copy = block.copy or {}
+        block.left = norm(line:match("^copy from (.*)"), false)
+        block.copy.from = block.left
       elseif line:find("^copy to") then
-        block.type = "copy"
-        block.right = norm(line:match("^copy to (.*)"))
+        block.copy = block.copy or {}
+        block.right = norm(line:match("^copy to (.*)"), false)
+        block.copy.to = block.right
       elseif line:find("^new file mode") then
-        block.type = "new"
+        block.new = line:match("^new file mode (.*)")
       elseif line:find("^deleted file mode") then
-        block.type = "delete"
-      elseif line:find("^old mode") or line:find("^new mode") then
-        block.type = "mode"
+        block.delete = line:match("^deleted file mode (.*)")
+      elseif line:find("^old mode") then
+        block.mode = block.mode or {}
+        block.mode.from = line:match("^old mode (.*)")
+      elseif line:find("^new mode") then
+        block.mode = block.mode or {}
+        block.mode.to = line:match("^new mode (.*)")
+      elseif line:find("^similarity index") then
+        local sim = line:match("^similarity index (%d+)%%")
+        block.similarity = tonumber(sim) or 0
+      elseif line:find("^dissimilarity index") then
+        local dis = line:match("^dissimilarity index (%d+)%%")
+        block.dissimilarity = tonumber(dis) or 0
+      elseif line:find("^index ") then
+        local from, to, mode = line:match("^index (%S+)%.%.(%S+)%s*(%d*)$")
+        block.index = { from = from, to = to, mode = mode ~= "" and mode or nil }
       end
     end
     local first = block.header[1] or ""
@@ -191,29 +223,53 @@ function M.parse(lines)
       }
     elseif text:find("@@", 1, true) == 1 and block then
       -- Hunk header
-      local line = 1
-      if text:find("@@@", 1, true) == 1 then
-        line = tonumber(text:match("^@@@ %-%d+,?%d* %-%d+,?%d* %+(%d+),?%d* @@@")) or 1
-        block.unmerged = true
+      hunk = M.parse_hunk_header(text)
+      if hunk then
+        block.unmerged = block.unmerged or (hunk.parents ~= nil) or nil
+        block.hunks[#block.hunks + 1] = hunk
       else
-        line = tonumber(text:match("^@@ %-%d+,?%d* %+(%d+),?%d* @@")) or 1
+        Snacks.notify.error("Invalid hunk header: " .. text, { title = "Snacks Picker Diff" })
       end
-      hunk = {
-        line = line,
-        diff = { text },
-      }
-      block.hunks[#block.hunks + 1] = hunk
     elseif hunk then
       -- Hunk body
       hunk.diff[#hunk.diff + 1] = text
     elseif block then
       block.header[#block.header + 1] = text
     else
-      Snacks.notify.error("unexpected line: " .. text, { title = "Snacks Picker Diff" })
+      Snacks.notify.error("Unexpected line: " .. text, { title = "Snacks Picker Diff" })
     end
   end
   emit()
   return ret
 end
 
+---@param line string
+function M.parse_hunk_header(line)
+  local count_start, inner, count_end, context = line:match("^(@+)%s*(.-)%s*(@+)%s*(.*)$")
+  if not count_start or not count_end or count_start ~= count_end or #count_start < 2 then
+    return
+  end
+  local ret = {} ---@type {line:number, count:number}[]
+  for _, part in ipairs(vim.split(inner, "%s+")) do
+    local l, c = part:match("^[%-+](%d+),?(%d*)$")
+    if not l then
+      return
+    end
+    ret[#ret + 1] = { line = tonumber(l) or 1, count = tonumber(c) or 1 }
+  end
+  if #ret ~= #count_start then
+    return
+  end
+  local right = table.remove(ret)
+  ---@type snacks.picker.diff.Hunk
+  return {
+    diff = { line },
+    line = right and right.line or 1,
+    left = table.remove(ret, 1),
+    right = right,
+    parents = #ret > 0 and ret or nil,
+    context = context ~= "" and context or nil,
+  }
+end
+
 return M