--- The `:Heph <subcommand>` user-command surface. Tactical/Organizational task
--- views (next/list/capture/...) arrive with slice 11b; this is the knowledge-
--- base core (journal, links).

local M = {}

--- subcommand -> handler(args: string[])
M.subs = {
  today = function()
    require("heph.journal").open()
  end,
  journal = function(args)
    require("heph.journal").open(args[1])
  end,
  follow = function()
    require("heph.link").follow()
  end,
  open = function(args)
    if args[1] then
      require("heph.node").open(args[1])
    end
  end,
}

--- `:Heph` entry point.
function M.run(opts)
  local args = opts.fargs
  local sub = args[1]
  if not sub then
    require("heph.util").notify("usage: :Heph <" .. table.concat(M.names(), "|") .. ">", vim.log.levels.WARN)
    return
  end
  local handler = M.subs[sub]
  if not handler then
    require("heph.util").notify("unknown subcommand: " .. sub, vim.log.levels.ERROR)
    return
  end
  local ok, err = pcall(handler, vim.list_slice(args, 2))
  if not ok then
    require("heph.util").notify(tostring(err), vim.log.levels.ERROR)
  end
end

--- Sorted subcommand names.
function M.names()
  local names = vim.tbl_keys(M.subs)
  table.sort(names)
  return names
end

--- Completion: subcommand names at the first position.
function M.complete(arglead, cmdline, _cursorpos)
  -- Only complete the subcommand token (first arg after :Heph).
  if cmdline:match("^%s*Heph%s+%S*$") then
    return vim.tbl_filter(function(n)
      return n:find(arglead, 1, true) == 1
    end, M.names())
  end
  return {}
end

return M