--- Task list views (tech-spec §8): Tactical `next` (the "what is next?" ranking)
--- and Organizational `list` (the whole outstanding set). Both render the same
--- titled rows the daemon returns into a scratch buffer; `<CR>` opens the task
--- under the cursor's canonical-context doc (the one-keystroke jump).

local rpc = require("heph.rpc")

local M = {}

-- buf -> { tasks = <RankedTask[]> }; line N maps to tasks[N].
M._views = {}

local function row(t)
  local tag = t.attention and ("[" .. t.attention .. "]") or "[ ]"
  return string.format("%s %s", tag, t.title)
end

-- Find or create the named scratch buffer and fill it with task rows.
local function render(name, tasks)
  local buf
  for _, b in ipairs(vim.api.nvim_list_bufs()) do
    if vim.api.nvim_buf_get_name(b) == name then
      buf = b
      break
    end
  end
  if not buf then
    buf = vim.api.nvim_create_buf(false, true) -- unlisted scratch
    vim.api.nvim_buf_set_name(buf, name)
  end
  vim.bo[buf].buftype = "nofile"
  vim.bo[buf].bufhidden = "hide"
  vim.bo[buf].swapfile = false

  local lines = {}
  for _, t in ipairs(tasks) do
    lines[#lines + 1] = row(t)
  end
  if #lines == 0 then
    lines = { "(nothing here)" }
  end
  vim.bo[buf].modifiable = true
  vim.api.nvim_buf_set_lines(buf, 0, -1, false, lines)
  vim.bo[buf].modifiable = false

  M._views[buf] = { tasks = tasks }
  vim.keymap.set("n", "<CR>", function()
    M.open_under_cursor(buf)
  end, { buffer = buf, desc = "heph: open task context" })
  vim.api.nvim_set_current_buf(buf)
  return buf
end

--- Open the canonical-context doc of the task on the cursor line.
function M.open_under_cursor(buf)
  buf = buf or vim.api.nvim_get_current_buf()
  local view = M._views[buf]
  if not view then
    return
  end
  local lnum = vim.api.nvim_win_get_cursor(0)[1]
  local t = view.tasks[lnum]
  if not t then
    return
  end
  require("heph.node").open(t.canonical_context_id or t.node_id)
end

--- Tactical "what is next?" — render the ranking, return the rows.
function M.next(opts)
  opts = opts or {}
  local tasks = rpc.call("next", { scope = opts.scope, limit = opts.limit or 5 })
  render("heph://next", tasks)
  return tasks
end

--- Organizational survey — render the outstanding set, return the rows.
function M.list(opts)
  opts = opts or {}
  local tasks = rpc.call("list", {
    scope = opts.scope,
    attention = opts.attention,
    include_blue = opts.include_blue ~= false,
  })
  render("heph://list", tasks)
  return tasks
end

return M