--- Buffer-backed nodes (tech-spec §8): a node's markdown body is edited in a
--- real buffer named `heph://node/<id>`. `:e` loads it via `node.get`; `:w`
--- saves the whole buffer back via `node.update` (the backend CRDT-diffs the
--- whole-buffer text, so sending the full body is correct and idempotent).

local rpc = require("heph.rpc")
local util = require("heph.util")

local M = {}

--- `BufReadCmd` handler for `heph://node/<id>`: load the body into the buffer.
function M.read(buf, uri)
  local _, id = util.parse_uri(uri)
  if not id then
    error("heph: not a node uri: " .. tostring(uri))
  end
  local node = rpc.call("node.get", { id = id })
  local body = (node and node.body) or ""
  -- `plain` split keeps a trailing "" element for a trailing newline, so the
  -- body round-trips exactly through `table.concat` on write.
  vim.api.nvim_buf_set_lines(buf, 0, -1, false, vim.split(body, "\n", { plain = true }))
  vim.b[buf].heph_node_id = id
  vim.b[buf].heph_node_kind = (node and node.kind) or "doc"
  vim.bo[buf].buftype = "acwrite" -- written via BufWriteCmd, not to a file
  vim.bo[buf].filetype = "markdown"
  vim.bo[buf].fileformat = "unix"
  vim.bo[buf].modified = false
  require("heph.link").attach(buf)
end

--- `BufWriteCmd` handler: persist the whole buffer as the node body.
function M.write(buf, _uri)
  local id = vim.b[buf].heph_node_id
  if not id then
    error("heph: buffer has no heph node id")
  end
  local lines = vim.api.nvim_buf_get_lines(buf, 0, -1, false)
  rpc.call("node.update", { id = id, body = table.concat(lines, "\n") })
  vim.bo[buf].modified = false
end

--- Open (or focus) the buffer for node `id`.
function M.open(id)
  vim.cmd.edit(util.node_uri(id))
end

--- Force-reload the buffer for node `id` from the daemon (discards local edits).
function M.reload(id)
  vim.cmd("edit! " .. vim.fn.fnameescape(util.node_uri(id)))
end

return M