Add nvim-cmp completion

Add autocompletion for commands and contexts using nvim-cmp.
Introduces a new filetype called "eca-input" for the chat window that
activates the completions.

Author: tomgeorge

lua/eca/completion/cmp/commands.lua

@@ -0,0 +1,98 @@
+---@param commands eca.ChatCommand
+---@return lsp.CompletionItem[]
+local function create_completion_items(commands)
+  ---@type lsp.CompletionItem[]
+  local items = {}
+
+  if commands then
+    for _, command in ipairs(commands) do
+      ---@type lsp.CompletionItem
+      local item = {
+        label = command.name or command.command,
+        kind = vim.lsp.protocol.CompletionItemKind.Function,
+        detail = command.description or ("ECA command: " .. (command.name or command.command)),
+        documentation = command.help and {
+          kind = "markdown",
+          value = command.help,
+        } or nil,
+        insertText = command.name or command.command,
+      }
+      table.insert(items, item)
+    end
+  end
+
+  return items
+end
+
+---@param s string
+---@return string
+local function get_query(s)
+  local match = s:match("^>?%s*/(.*)$")
+  return match
+end
+
+-- Query server for available commands
+local function query_server_commands(query, callback)
+  local eca = require("eca")
+  if not eca.server or not eca.server:is_running() then
+    callback({})
+    return
+  end
+
+  eca.server:send_request("chat/queryCommands", { query = query }, function(err, result)
+    if err then
+      callback({})
+      return
+    end
+
+    local items = create_completion_items(result.commands)
+    callback(items)
+  end)
+end
+
+local source = {}
+
+source.new = function()
+  return setmetatable({ cache = {} }, { __index = source })
+end
+
+source.get_trigger_characters = function()
+  return { "/" }
+end
+
+source.is_available = function()
+  return vim.bo.filetype == "eca-input"
+end
+
+---@diagnostic disable-next-line: unused-local
+source.complete = function(self, _, callback)
+  local logger = require("eca.logger")
+  -- Only complete if we're typing a command (starts with /)
+  local line = vim.api.nvim_get_current_line()
+  local query = get_query(line)
+
+  -- Only provide command completions when we have / followed by word characters or at word boundary
+  if query then
+    local bufnr = vim.api.nvim_get_current_buf()
+
+    if self.cache[bufnr] and self.cache[bufnr][query] then
+      callback({ items = self.cache[bufnr][query], isIncomplete = false })
+    else
+      logger.debug("not cached")
+      query_server_commands(query, function(items)
+        callback({
+          items = items,
+          isIncomplete = false,
+        })
+        self.cache[bufnr] = {}
+        self.cache[bufnr][query] = items
+      end)
+    end
+  else
+    callback({
+      items = {},
+      isIncomplete = false,
+    })
+  end
+end
+return source

lua/eca/completion/cmp/context.lua

@@ -0,0 +1,148 @@
+local Logger = require("eca.logger")
+local cmp = require("cmp")
+---@param context eca.ChatContext
+---@return lsp.CompletionItem
+local function as_completion_item(context)
+  ---@type lsp.CompletionItem
+  ---@diagnostic disable-next-line: missing-fields
+  local item = {}
+  if context.type == "file" then
+    item.label = string.format("@%s", vim.fn.fnamemodify(context.path, ":."))
+    item.kind = cmp.lsp.CompletionItemKind.File
+    item.data = {
+      context_item = context,
+    }
+  elseif context.type == "directory" then
+    item.label = string.format("@%s", vim.fn.fnamemodify(context.path, ":."))
+    item.kind = cmp.lsp.CompletionItemKind.Folder
+  elseif context.type == "web" then
+    item.label = context.url
+    item.kind = cmp.lsp.CompletionItemKind.File
+  elseif context.type == "repoMap" then
+    item.label = "repoMap"
+    item.kind = cmp.lsp.CompletionItemKind.Module
+    item.detail = "Summary view of workspace files."
+  elseif context.type == "mcpResource" then
+    item.label = string.format("%s:%s", context.server, context.name)
+    item.kind = cmp.lsp.CompletionItemKind.Struct
+    item.detail = context.description
+  end
+  if not item.label then
+    return {}
+  end
+  return item
+end
+
+-- Query server for available contexts
+-- @param query string
+--
+local function query_server_contexts(query, callback)
+  local eca = require("eca")
+  if not eca.server or not eca.server:is_running() then
+    callback({})
+    return
+  end
+
+  eca.server:send_request("chat/queryContext", { query = query }, function(err, result)
+    Logger.debug("chat/queryContext query " .. vim.inspect({ query = query }))
+    if err then
+      Logger.debug("chat/queryContext err: " .. err)
+      callback({})
+      return
+    end
+
+    local items = vim.iter(result.contexts):map(as_completion_item):totable()
+    callback({ items = items, isIncomplete = true })
+  end)
+end
+
+local source = {}
+
+function source.new()
+  return setmetatable({}, { __index = source })
+end
+
+function source:get_trigger_characters()
+  return { "@" }
+end
+
+function source:get_keyword_pattern()
+  return [[\k\+]]
+end
+
+function source:is_available()
+  return vim.bo.filetype == "eca-input"
+end
+
+---@param cursor_line string
+---@param cursor_position lsp.Position|vim.Position
+---@return string
+local function get_query(cursor_line, cursor_position)
+  local before_cursor = cursor_line:sub(1, cursor_position.col)
+  ---@type string[]
+  local matches = {}
+  local it = before_cursor:gmatch("@([%w%./_\\%-~]*)")
+  for match in it do
+    table.insert(matches, match)
+  end
+  return matches[#matches]
+end
+
+---@param params cmp.SourceCompletionApiParams
+---@diagnostic disable-next-line: unused-local
+function source:complete(params, callback)
+  local query = get_query(params.context.cursor_line, params.context.cursor)
+  if query then
+    query_server_contexts(query, function(items)
+      callback(items)
+    end)
+  end
+end
+
+--- Taken from https://github.com/hrsh7th/cmp-path/blob/9a16c8e5d0be845f1d1b64a0331b155a9fe6db4d/lua/cmp_path/init.lua
+--- Show a small preview of file contexft items in the documentation window.
+---@param data eca.ChatContext
+---@return lsp.MarkupContent
+source._get_documentation = function(_, data, count)
+  if data and data.path then
+    local filename = data.path
+    local binary = assert(io.open(data.path, "rb"))
+    local first_kb = binary:read(1024)
+    if first_kb and first_kb:find("\0") then
+      return { kind = vim.lsp.protocol.MarkupKind.PlainText, value = "binary file" }
+    end
+
+    local content = io.lines(data.path)
+
+    --- Try to support line ranges, I don't know if this works or not yet
+    local start = data.lines_range and data.lines_range.start or 1
+    local last = data.lines_range and data.lines_range["end"] or count
+    local skip_lines = start - 1
+    local take_lines = last - start
+    local contents = vim.iter(content):skip(skip_lines):take(take_lines):totable()
+
+    local filetype = vim.filetype.match({ filename = filename })
+    if not filetype then
+      return { kind = vim.lsp.protocol.MarkupKind.PlainText, value = table.concat(contents, "\n") }
+    end
+
+    table.insert(contents, 1, "```" .. filetype)
+    table.insert(contents, "```")
+    return { kind = vim.lsp.protocol.MarkupKind.Markdown, value = table.concat(contents, "\n") }
+  end
+  return {}
+end
+
+---@param completion_item lsp.CompletionItem
+function source:resolve(completion_item, callback)
+  if completion_item.data then
+    local context_item = completion_item.data.context_item
+    ---@cast context_item eca.ChatContext
+    if context_item.type == "file" then
+      completion_item.documentation = self:_get_documentation(context_item, 20)
+    end
+    callback(completion_item)
+  end
+end
+
+return source

lua/eca/completion/cmp/init.lua

@@ -0,0 +1,18 @@
+local cmp = require("cmp")
+
+vim.api.nvim_create_autocmd("FileType", {
+  pattern = "eca-input",
+  callback = function()
+    cmp.register_source("eca_commands", require("eca.completion.cmp.commands").new())
+    cmp.register_source("eca_contexts", require("eca.completion.cmp.context").new())
+    cmp.setup.filetype("eca-input", {
+      sources = {
+        { name = "eca_contexts" },
+        { name = "eca_commands" },
+      },
+    })
+    -- returning true will remove this autocmd
+    -- now that the completion sources are registered
+    return true
+  end,
+})

lua/eca/sidebar.lua

@@ -367,6 +367,7 @@ function M:_create_containers()
     size = { height = input_height },
     buf_options = vim.tbl_deep_extend("force", base_buf_options, {
       modifiable = true,
+      filetype = "eca-input",
     }),
     win_options = vim.tbl_deep_extend("force", base_win_options, {
       statusline = " ",

lua/eca/types.lua

@@ -0,0 +1,19 @@
+---@meta
+---@class eca.ChatContext
+---@field type string
+---@field path? string
+---@field lines_range? {start: integer, end: integer}
+---@field url? string
+---@field uri? string
+---@field name? string
+---@field description? string
+---@field mime_type? string
+---@field server string
+---
+---
+---@class eca.ChatCommand
+---@field name string
+---@field description string
+---@field help string
+---@field type "mcp-prompt"|"native"
+---@field arguments {name: string, description?: string, required: boolean}[]