--- jasper/api.lua
--- Low-level HTTP calls to the Jasper API, executed via curl.

local M = {}

local JASPER_URL = "https://jasper.4sigma.it"

--- Run a curl command and return the parsed JSON body + HTTP status code.
--- @param args string[]  full curl argument list (without the URL, which is last)
--- @return table|nil  decoded JSON body
--- @return number     HTTP status code (0 on curl error)
--- @return string|nil error message
local function curl(args)
  -- Append -w to get the HTTP status on a separate last line
  local full_args = vim.list_extend(vim.list_slice(args, 1), { "-s", "-w", "\n%{http_code}" })
  -- args already contains the URL; rebuild properly:
  -- Actually we receive the full arg list already.  Add -w trick.
  table.insert(args, "-w")
  table.insert(args, "\n%{http_code}")

  local result = vim.system(args, { text = true }):wait()
  if result.code ~= 0 then
    return nil, 0, "curl error (exit " .. result.code .. ")"
  end

  -- Split body and status code
  local last_newline = result.stdout:match(".*\n()")
  local status_code = tonumber(result.stdout:sub(last_newline)) or 0
  local body = result.stdout:sub(1, last_newline - 2) -- strip trailing \n + status line

  local ok, data = pcall(vim.fn.json_decode, body)
  if not ok then
    return nil, status_code, "JSON decode error"
  end
  return data, status_code, nil
end

--- @param path string  API path, e.g. "/api/v1/timer/"
--- @param token string
--- @return table|nil, number, string|nil
local function get(path, token)
  return curl({
    "curl",
    "-H", "Authorization: Token " .. token,
    JASPER_URL .. path,
  })
end

--- @param path string
--- @param token string
--- @param form table<string,any>|nil  key/value pairs sent as form data
--- @return table|nil, number, string|nil
local function post(path, token, form)
  local args = {
    "curl", "-X", "POST",
    "-H", "Authorization: Token " .. token,
  }
  if form then
    for k, v in pairs(form) do
      table.insert(args, "--data-urlencode")
      table.insert(args, k .. "=" .. tostring(v))
    end
  end
  table.insert(args, JASPER_URL .. path)
  return curl(args)
end

-- ---------------------------------------------------------------------------
-- Public API
-- ---------------------------------------------------------------------------

--- Fetch all timers for the current user.
--- @param token string
--- @return table[]|nil  list of timer objects
--- @return string|nil   error message
function M.get_timers(token)
  local data, status, err = get("/api/v1/timer/", token)
  if err then
    return nil, err
  end
  if status == 401 then
    return nil, "unauthorized"
  end
  if status ~= 200 then
    return nil, "unexpected HTTP status " .. status
  end
  local timers_dict = data.data and data.data.timers
  if type(timers_dict) ~= "table" then
    return nil, "unexpected response shape"
  end
  local timers = {}
  for _, v in pairs(timers_dict) do
    table.insert(timers, v)
  end
  return timers, nil
end

--- Start (play) a timer.
--- @param token string
--- @param timer_id number
--- @return boolean ok
--- @return string|nil error
function M.start_timer(token, timer_id)
  local data, status, err = post("/api/v1/timer/" .. timer_id .. "/play/", token)
  if err then
    return false, err
  end
  if status ~= 200 then
    return false, "HTTP " .. status
  end
  if data.error ~= nil and data.error ~= vim.NIL then
    return false, tostring(data.error)
  end
  return true, nil
end

--- Pause a timer.
--- @param token string
--- @param timer_id number
--- @return boolean ok
--- @return string|nil error
function M.stop_timer(token, timer_id)
  local data, status, err = post("/api/v1/timer/" .. timer_id .. "/pausa/", token)
  if err then
    return false, err
  end
  if status ~= 200 then
    return false, "HTTP " .. status
  end
  if data.error ~= nil and data.error ~= vim.NIL then
    return false, tostring(data.error)
  end
  return true, nil
end

--- Associate an attivita with a (new) timer slot.
--- @param token string
--- @param timer_id number   desired slot id (smallest free integer)
--- @param attivita_id number
--- @return boolean ok
--- @return string|nil error
function M.create_timer(token, timer_id, attivita_id)
  local data, status, err = post(
    "/api/v1/timer/" .. timer_id .. "/attivita/",
    token,
    { attivita_id = attivita_id }
  )
  if err then
    return false, err
  end
  if status ~= 200 then
    return false, "HTTP " .. status
  end
  if data.error ~= nil and data.error ~= vim.NIL then
    return false, tostring(data.error)
  end
  return true, nil
end

return M