--- Daily journal (tech-spec §8). `journal.open_or_create` is idempotent (the
--- node id is deterministic in (owner, date)), so opening today's note twice is
--- safe.

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

local M = {}

--- Open (creating if absent) the journal for `date` (default: today), in a
--- buffer. Returns the node.
function M.open(date)
  date = date or util.iso_today()
  local node = rpc.call("journal.open_or_create", { date = date })
  require("heph.node").open(node.id)
  return node
end

local function iso_to_time(iso)
  local y, m, d = iso:match("(%d+)-(%d+)-(%d+)")
  return os.time({ year = tonumber(y), month = tonumber(m), day = tonumber(d), hour = 12 })
end

--- Entries for the `n` most recent days ending at `today` (ISO; default today),
--- newest first. Each: `{ date, node|nil, exists }`. Journals are titled by
--- their ISO date, so each day resolves directly.
function M.recent_entries(n, today)
  today = (today and #today > 0) and today or util.iso_today()
  local t0 = iso_to_time(today)
  local entries = {}
  for i = 0, n - 1 do
    local date = os.date("%Y-%m-%d", t0 - i * 86400)
    local node = rpc.call("node.resolve", { title = date })
    entries[#entries + 1] = { date = date, node = node, exists = node ~= nil }
  end
  return entries
end

--- Pick among recent journal days — existing days preview their content, new
--- days show `@create` — and open the chosen day's journal (creating if new).
function M.pick(opts)
  opts = opts or {}
  local days = opts.days or (require("heph").config or {}).journal_days or 7
  require("heph.picker").select(M.recent_entries(days), {
    prompt = "heph journals",
    format = function(e)
      return e.exists and e.date or (e.date .. "   @create")
    end,
    preview = function(e)
      if e.exists and e.node and e.node.body and #e.node.body > 0 then
        return vim.split(e.node.body, "\n", { plain = true })
      end
      return { "@create — new journal for " .. e.date }
    end,
  }, function(e)
    if e then
      M.open(e.date)
    end
  end)
end

return M