-- Language-aware project runner.
--
-- Detects what kind of project the current buffer lives in and exposes a small
-- set of verbs (run / run file / build / test / flash / ...) that map onto the
-- right tool for that project. Bound under <leader>R -- see
-- lua/plugins/project-run.lua.
--
-- Everything is discovered from the project on disk; nothing is hardcoded to a
-- machine, and per-project choices (like the Zephyr board) are cached in
-- stdpath("state") rather than written into the repo.

local M = {}

---------------------------------------------------------------------------
-- helpers
---------------------------------------------------------------------------

--- The file the project should be judged from.
---
--- Not simply the current buffer: after one of these verbs opens a terminal,
--- that terminal is the focused buffer, and walking up from it finds no project
--- markers. So prefer the focused buffer only when it is a real file, and
--- otherwise fall back to the most recently used normal buffer, then cwd.
---@return string
function M.source_path()
  local buf = vim.api.nvim_get_current_buf()
  if vim.bo[buf].buftype == "" then
    local name = vim.api.nvim_buf_get_name(buf)
    if name ~= "" then
      return name
    end
  end

  -- Tracked by the autocmd in lua/plugins/project-run.lua.
  local last = vim.g.project_last_file
  if type(last) == "string" and last ~= "" then
    return last
  end

  return vim.uv.cwd()
end

---@param markers string[]
---@return string|nil
local function root_with(markers)
  return vim.fs.root(M.source_path(), markers)
end

local function exists(path)
  return path and vim.uv.fs_stat(path) ~= nil
end

--- Run a command in a terminal at `cwd` so you can watch it and answer prompts.
local function term(cmd, cwd, opts)
  opts = opts or {}
  local ok, Snacks = pcall(require, "snacks")
  if ok and Snacks.terminal then
    Snacks.terminal.open(cmd, {
      cwd = cwd,
      interactive = true,
      win = { position = opts.position or "float" },
    })
  else
    vim.cmd("botright split | terminal " .. cmd)
  end
  vim.notify(cmd, vim.log.levels.INFO, { title = "project" })
end

--- Prefer a project-local virtualenv interpreter when there is one.
local function python_for(root)
  for _, rel in ipairs({ ".venv/bin/python", "venv/bin/python" }) do
    local p = vim.fs.joinpath(root, rel)
    if exists(p) then
      return vim.fn.shellescape(p)
    end
  end
  return "python3"
end

---------------------------------------------------------------------------
-- per-project state (board selection, etc.)
---------------------------------------------------------------------------

local state_file = vim.fs.joinpath(vim.fn.stdpath("state"), "project-run.json")

local function load_state()
  if not exists(state_file) then
    return {}
  end
  local ok, data = pcall(function()
    return vim.json.decode(table.concat(vim.fn.readfile(state_file), "\n"))
  end)
  return (ok and type(data) == "table") and data or {}
end

local function save_state(tbl)
  pcall(vim.fn.writefile, vim.fn.split(vim.json.encode(tbl), "\n"), state_file)
end

---@param root string
---@param key string
function M.get_setting(root, key)
  local s = load_state()
  return (s[root] or {})[key]
end

---@param root string
---@param key string
---@param value any
function M.set_setting(root, key, value)
  local s = load_state()
  s[root] = s[root] or {}
  s[root][key] = value
  save_state(s)
end

---------------------------------------------------------------------------
-- project detection
---------------------------------------------------------------------------

--- Order matters: a Zephyr app is also a CMake project, so it must win.
local DETECT = {
  { type = "zephyr", markers = { "west.yml", ".west", "prj.conf" } },
  { type = "rust", markers = { "Cargo.toml" } },
  { type = "python", markers = { "pyproject.toml", "setup.py", "requirements.txt" } },
  { type = "cmake", markers = { "CMakeLists.txt", "CMakePresets.json" } },
  { type = "make", markers = { "Makefile" } },
}

---@return string type, string root
function M.detect()
  for _, d in ipairs(DETECT) do
    local root = root_with(d.markers)
    if root then
      -- A Zephyr app has prj.conf next to CMakeLists.txt; plain CMake does not.
      return d.type, root
    end
  end
  return "unknown", vim.uv.cwd()
end

function M.info()
  local t, root = M.detect()
  local extra = ""
  if t == "zephyr" then
    extra = "  board: " .. (M.get_setting(root, "board") or "<not set>")
  end
  vim.notify(("project: %s\nroot: %s%s"):format(t, root, extra), vim.log.levels.INFO, { title = "project" })
end

---------------------------------------------------------------------------
-- Zephyr
---------------------------------------------------------------------------

local board_list_cache = nil

--- `west boards` walks the whole tree and is slow, so cache the result.
local function zephyr_boards(root, cb)
  if board_list_cache then
    return cb(board_list_cache)
  end
  vim.notify("listing boards (west boards)...", vim.log.levels.INFO, { title = "zephyr" })
  vim.system({ "west", "boards", "-f", "{name}" }, { cwd = root, text = true }, function(res)
    vim.schedule(function()
      if res.code ~= 0 then
        vim.notify("west boards failed:\n" .. (res.stderr or ""), vim.log.levels.ERROR, { title = "zephyr" })
        return cb({})
      end
      local boards = {}
      for _, line in ipairs(vim.split(res.stdout or "", "\n")) do
        line = vim.trim(line)
        if line ~= "" then
          boards[#boards + 1] = line
        end
      end
      table.sort(boards)
      board_list_cache = boards
      cb(boards)
    end)
  end)
end

--- Pick a board with the configured fuzzy picker (vim.ui.select is routed to it).
---@param root string
---@param cb fun(board:string)|nil
function M.zephyr_select_board(root, cb)
  root = root or select(2, M.detect())
  zephyr_boards(root, function(boards)
    if #boards == 0 then
      return
    end
    vim.ui.select(boards, { prompt = "Zephyr board:" }, function(choice)
      if not choice then
        return
      end
      M.set_setting(root, "board", choice)
      vim.notify("board = " .. choice, vim.log.levels.INFO, { title = "zephyr" })
      if cb then
        cb(choice)
      end
    end)
  end)
end

--- Get the board, prompting for one if it has not been chosen yet.
local function with_board(root, cb)
  local board = M.get_setting(root, "board")
  if board then
    return cb(board)
  end
  M.zephyr_select_board(root, cb)
end

local function zephyr_build_dir(root)
  return M.get_setting(root, "build_dir") or "build"
end

---------------------------------------------------------------------------
-- verbs
---------------------------------------------------------------------------

--- Primary "run this project".
function M.run()
  local t, root = M.detect()
  if t == "rust" then
    term("cargo run", root)
  elseif t == "python" then
    local py = python_for(root)
    -- main.py at the root wins; then any package with a __main__.py.
    if exists(vim.fs.joinpath(root, "main.py")) then
      term(py .. " main.py", root)
      return
    end
    local mains = vim.fs.find("__main__.py", { path = root, type = "file", limit = 5 })
    if #mains > 0 then
      local dir = vim.fs.dirname(mains[1])
      local pkg = vim.fs.basename(dir)
      local parent = vim.fs.dirname(dir)
      -- run as a module so intra-package imports resolve
      term(("PYTHONPATH=%s %s -m %s"):format(vim.fn.shellescape(parent), py, pkg), root)
      return
    end
    M.run_file()
  elseif t == "zephyr" then
    M.flash()
  elseif t == "cmake" then
    -- run the first executable cmake produced, if we can find one
    local bin = vim.fs.find(function(name, path)
      return path:match("/build$") ~= nil and vim.fn.executable(vim.fs.joinpath(path, name)) == 1
    end, { path = vim.fs.joinpath(root, "build"), type = "file", limit = 1 })[1]
    if bin then
      term(vim.fn.shellescape(bin), root)
    else
      vim.notify("no executable found in build/ -- build first", vim.log.levels.WARN, { title = "project" })
    end
  elseif t == "make" then
    term("make run", root)
  else
    M.run_file()
  end
end

--- Run just the current file.
function M.run_file()
  local file = M.source_path()
  if file == "" or vim.fn.filereadable(file) == 0 then
    return vim.notify("no file to run", vim.log.levels.WARN, { title = "project" })
  end
  local _, root = M.detect()
  local ft = vim.filetype.match({ filename = file }) or vim.bo.filetype
  local runners = {
    python = function()
      return python_for(root) .. " " .. vim.fn.shellescape(file)
    end,
    lua = function()
      return "lua " .. vim.fn.shellescape(file)
    end,
    sh = function()
      return "bash " .. vim.fn.shellescape(file)
    end,
    rust = function()
      return "cargo run"
    end,
    go = function()
      return "go run " .. vim.fn.shellescape(file)
    end,
  }
  local build = runners[ft]
  if not build then
    -- Compiled languages have no meaningful "run this one file"; say what to
    -- use instead rather than just refusing.
    return vim.notify(
      ("no single-file runner for '%s' -- use <leader>Rr to run the project"):format(ft),
      vim.log.levels.WARN,
      { title = "project" }
    )
  end
  term(build(), root)
end

function M.build()
  local t, root = M.detect()
  if t == "zephyr" then
    with_board(root, function(board)
      term(("west build -b %s -d %s ."):format(board, zephyr_build_dir(root)), root)
    end)
  elseif t == "rust" then
    term("cargo build", root)
  elseif t == "cmake" then
    term("cmake -S . -B build -DCMAKE_EXPORT_COMPILE_COMMANDS=ON && cmake --build build", root)
  elseif t == "make" then
    term("make", root)
  elseif t == "python" then
    term(python_for(root) .. " -m build", root)
  else
    vim.notify("no build for project type '" .. t .. "'", vim.log.levels.WARN, { title = "project" })
  end
end

function M.test()
  local t, root = M.detect()
  if t == "rust" then
    term("cargo test", root)
  elseif t == "python" then
    term(python_for(root) .. " -m pytest", root)
  elseif t == "zephyr" then
    with_board(root, function(board)
      term(("west twister -p %s -T ."):format(board), root)
    end)
  elseif t == "cmake" then
    term("ctest --test-dir build --output-on-failure", root)
  elseif t == "make" then
    term("make test", root)
  else
    vim.notify("no test for project type '" .. t .. "'", vim.log.levels.WARN, { title = "project" })
  end
end

--- Zephyr flash (and the obvious analogue elsewhere).
function M.flash()
  local t, root = M.detect()
  if t ~= "zephyr" then
    return vim.notify("flash is Zephyr-only (project is '" .. t .. "')", vim.log.levels.WARN, { title = "project" })
  end
  with_board(root, function(board)
    term(("west build -b %s -d %s . && west flash -d %s"):format(board, zephyr_build_dir(root), zephyr_build_dir(root)), root)
  end)
end

function M.clean()
  local t, root = M.detect()
  if t == "zephyr" then
    term("west build -t pristine -d " .. zephyr_build_dir(root), root)
  elseif t == "rust" then
    term("cargo clean", root)
  elseif t == "cmake" then
    term("cmake --build build --target clean", root)
  elseif t == "make" then
    term("make clean", root)
  else
    vim.notify("no clean for project type '" .. t .. "'", vim.log.levels.WARN, { title = "project" })
  end
end

--- Zephyr menuconfig / rust clippy / python lint -- the "configure" slot.
function M.configure()
  local t, root = M.detect()
  if t == "zephyr" then
    term("west build -t menuconfig -d " .. zephyr_build_dir(root), root)
  elseif t == "rust" then
    term("cargo clippy --all-targets", root)
  elseif t == "cmake" then
    term("cmake -S . -B build -DCMAKE_EXPORT_COMPILE_COMMANDS=ON", root)
  else
    vim.notify("nothing to configure for '" .. t .. "'", vim.log.levels.WARN, { title = "project" })
  end
end

--- Select the target: Zephyr board today, extensible later.
function M.select_target()
  local t, root = M.detect()
  if t == "zephyr" then
    M.zephyr_select_board(root)
  else
    vim.notify("no target to select for project type '" .. t .. "'", vim.log.levels.WARN, { title = "project" })
  end
end

return M