local M = {}

local util = require("fschauen.util")
local exists = util.exists

---Find lua module source.
---@param modname string Module name.
---@return table results List of source files in the runtime path that implement
---                      `modname`.
local find_module_sources = function(modname)
  modname = modname:gsub("^%.+", ""):gsub("/", ".")
  local base = "lua/" .. modname:gsub("%.", "/")
  local candidates = { base .. ".lua", base .. "/init.lua" }

  local results = {}
  for _, directory in ipairs(vim.opt.runtimepath:get()) do
    for _, candidate in ipairs(candidates) do
      local path = directory .. "/" .. candidate
      if exists(path) then table.insert(results, path) end
    end
  end
  return results
end

---Execute lua script in lines.
---@param first integer|nil First line to execute. If nil, execute current line.
---@param last integer|nil Last line to execute. If nil, execute only the first
---                       line.
M.execute_lines = function(first, last)
  first = first or vim.fn.line(".")
  last = last or first
  ---@diagnostic disable-next-line: param-type-mismatch
  local code = vim.fn.join(vim.fn.getline(first, last), "\n")
  loadstring(code)()
end

---Execute current selection as a lua chunk.
M.execute_selection = function()
  local selection = { vim.fn.line("v"), vim.fn.line(".") }
  table.sort(selection)
  M.execute_lines(unpack(selection))
end

---Execute lua script in a file.
---@param path string|nil Path to the file to execute. If nil, write and source
---                       current buffer.
M.execute_file = function(path)
  if not path then
    path = vim.fn.expand("%")
    vim.cmd.write()
  end
  vim.cmd.luafile(path)
end

---Edit a lua module.
---@param modname string|nil Module name. If nil, edit path name under cursor
---                          (meant to be mapped to `gf`).
M.go_to_module = function(modname)
  modname = modname or vim.fn.expand("<cfile>")

  local sources = find_module_sources(modname)
  if #sources == 0 then
    vim.notify("Not found: " .. modname, vim.log.levels.WARN)
  elseif #sources == 1 then
    vim.cmd.edit(sources[1])
  else
    vim.ui.select(sources, { prompt = "Which one?" }, function(choice)
      if choice then vim.cmd.edit(choice) end
    end)
  end
end

return M