-- opencode.nvim - Toggle opencode in a Neovim terminal.
-- SPDX-License-Identifier: GPL-3.0-only
-- Copyright (C) 2026 Asger Gitz-Johansen
--
-- This program is free software: you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation, version 3 only.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-- GNU General Public License for more details.

local M = {}

local state = {
  buf = nil,
  win = nil,
  job = nil,
}

local config = {
  width = 0.3,
  location = "right",
}

local valid_locations = {
  left = true,
  right = true,
  top = true,
  bottom = true,
}

local function is_valid_window(win)
  return win and vim.api.nvim_win_is_valid(win)
end

local function is_valid_buffer(buf)
  return buf and vim.api.nvim_buf_is_valid(buf)
end

local function terminal_width()
  return math.max(1, math.floor(vim.o.columns * config.width))
end

local function terminal_height()
  return math.max(1, math.floor(vim.o.lines * config.width))
end

local function open_terminal_window()
  if config.location == "left" then
    vim.cmd("topleft vertical " .. terminal_width() .. "new")
  elseif config.location == "right" then
    vim.cmd("botright vertical " .. terminal_width() .. "new")
  elseif config.location == "top" then
    vim.cmd("topleft " .. terminal_height() .. "new")
  else
    vim.cmd("botright " .. terminal_height() .. "new")
  end

  state.win = vim.api.nvim_get_current_win()

  if config.location == "left" or config.location == "right" then
    vim.api.nvim_set_option_value("winfixwidth", true, { win = state.win })
  else
    vim.api.nvim_set_option_value("winfixheight", true, { win = state.win })
  end
end

local function start_terminal()
  state.buf = vim.api.nvim_create_buf(false, true)
  vim.api.nvim_set_option_value("bufhidden", "hide", { buf = state.buf })
  vim.api.nvim_set_option_value("filetype", "opencode", { buf = state.buf })
  vim.api.nvim_buf_set_name(state.buf, "opencode")

  vim.api.nvim_win_set_buf(state.win, state.buf)
  state.job = vim.fn.termopen("opencode", {
    on_exit = function()
      state.job = nil
    end,
  })
end

function M.toggle()
  if is_valid_window(state.win) then
    vim.api.nvim_win_close(state.win, false)
    state.win = nil
    return
  end

  open_terminal_window()

  if is_valid_buffer(state.buf) then
    vim.api.nvim_win_set_buf(state.win, state.buf)
  else
    start_terminal()
  end

  vim.cmd("startinsert")
end

function M.setup(opts)
  opts = opts or {}

  if opts.width ~= nil then
    assert(
      type(opts.width) == "number" and opts.width > 0 and opts.width <= 1,
      "opencode.nvim: width must be a number between 0 and 1"
    )

    config.width = opts.width
  end

  if opts.location ~= nil then
    assert(
      type(opts.location) == "string" and valid_locations[opts.location],
      "opencode.nvim: location must be one of: left, right, top, bottom"
    )

    config.location = opts.location
  end

  vim.api.nvim_create_user_command("OpenCodeToggle", function()
    M.toggle()
  end, { force = true })

end

return M