local a = vim.api
local language = require'vim.treesitter.language'

-- query: pattern matching on trees
-- predicate matching is implemented in lua
local Query = {}
Query.__index = Query

local M = {}

---@private
local function dedupe_files(files)
  local result = {}
  local seen = {}

  for _, path in ipairs(files) do
    if not seen[path] then
      table.insert(result, path)
      seen[path] = true
    end
  end

  return result
end

---@private
local function safe_read(filename, read_quantifier)
  local file, err = io.open(filename, 'r')
  if not file then
    error(err)
  end
  local content = file:read(read_quantifier)
  io.close(file)
  return content
end

--- Gets the list of files used to make up a query
---
---@param lang The language
---@param query_name The name of the query to load
---@param is_included Internal parameter, most of the time left as `nil`
function M.get_query_files(lang, query_name, is_included)
  local query_path = string.format('queries/%s/%s.scm', lang, query_name)
  local lang_files = dedupe_files(a.nvim_get_runtime_file(query_path, true))

  if #lang_files == 0 then return {} end

  local base_langs = {}

  -- Now get the base languages by looking at the first line of every file
  -- The syntax is the following :
  -- ;+ inherits: ({language},)*{language}
  --
  -- {language} ::= {lang} | ({lang})
  local MODELINE_FORMAT = "^;+%s*inherits%s*:?%s*([a-z_,()]+)%s*$"

  for _, file in ipairs(lang_files) do
    local modeline = safe_read(file, '*l')

    if modeline then
      local langlist = modeline:match(MODELINE_FORMAT)

      if langlist then
        for _, incllang in ipairs(vim.split(langlist, ',', true)) do
          local is_optional = incllang:match("%(.*%)")

          if is_optional then
            if not is_included then
              table.insert(base_langs, incllang:sub(2, #incllang - 1))
            end
          else
            table.insert(base_langs, incllang)
          end
        end
      end
    end
  end

  local query_files = {}
  for _, base_lang in ipairs(base_langs) do
    local base_files = M.get_query_files(base_lang, query_name, true)
    vim.list_extend(query_files, base_files)
  end
  vim.list_extend(query_files, lang_files)

  return query_files
end

---@private
local function read_query_files(filenames)
  local contents = {}

  for _,filename in ipairs(filenames) do
    table.insert(contents, safe_read(filename, '*a'))
  end

  return table.concat(contents, '')
end

--- The explicitly set queries from |vim.treesitter.query.set_query()|
local explicit_queries = setmetatable({}, {
  __index = function(t, k)
    local lang_queries = {}
    rawset(t, k, lang_queries)

    return lang_queries
  end,
})

--- Sets the runtime query {query_name} for {lang}
---
--- This allows users to override any runtime files and/or configuration
--- set by plugins.
---
---@param lang string: The language to use for the query
---@param query_name string: The name of the query (i.e. "highlights")
---@param text string: The query text (unparsed).
function M.set_query(lang, query_name, text)
  explicit_queries[lang][query_name] = M.parse_query(lang, text)
end

--- Returns the runtime query {query_name} for {lang}.
---
---@param lang The language to use for the query
---@param query_name The name of the query (i.e. "highlights")
---
---@return The corresponding query, parsed.
function M.get_query(lang, query_name)
  if explicit_queries[lang][query_name] then
    return explicit_queries[lang][query_name]
  end

  local query_files = M.get_query_files(lang, query_name)
  local query_string = read_query_files(query_files)

  if #query_string > 0 then
    return M.parse_query(lang, query_string)
  end
end

--- Parse {query} as a string. (If the query is in a file, the caller
---       should read the contents into a string before calling).
---
--- Returns a `Query` (see |lua-treesitter-query|) object which can be used to
--- search nodes in the syntax tree for the patterns defined in {query}
--- using `iter_*` methods below.
---
--- Exposes `info` and `captures` with additional information about the {query}.
---   - `captures` contains the list of unique capture names defined in
---     {query}.
---   -` info.captures` also points to `captures`.
---   - `info.patterns` contains information about predicates.
---
---@param lang The language
---@param query A string containing the query (s-expr syntax)
---
---@returns The query
function M.parse_query(lang, query)
  language.require_language(lang)
  local self = setmetatable({}, Query)
  self.query = vim._ts_parse_query(lang, query)
  self.info = self.query:inspect()
  self.captures = self.info.captures
  return self
end

--- Gets the text corresponding to a given node
---
---@param node the node
---@param source The buffer or string from which the node is extracted
function M.get_node_text(node, source)
  local start_row, start_col, start_byte = node:start()
  local end_row, end_col, end_byte = node:end_()

  if type(source) == "number" then
    local lines
    local eof_row = a.nvim_buf_line_count(source)
    if start_row >= eof_row then
      return nil
    end

    if end_col == 0 then
      lines = a.nvim_buf_get_lines(source, start_row, end_row, true)
      end_col = -1
    else
      lines = a.nvim_buf_get_lines(source, start_row, end_row + 1, true)
    end

    if #lines == 1 then
      lines[1]      = string.sub(lines[1], start_col+1, end_col)
    else
      lines[1]      = string.sub(lines[1], start_col+1)
      lines[#lines] = string.sub(lines[#lines], 1, end_col)
    end

    return table.concat(lines, "\n")
  elseif type(source) == "string" then
    return source:sub(start_byte+1, end_byte)
  end
end

-- Predicate handler receive the following arguments
-- (match, pattern, bufnr, predicate)
local predicate_handlers = {
  ["eq?"] = function(match, _, source, predicate)
      local node = match[predicate[2]]
      local node_text = M.get_node_text(node, source)

      local str
      if type(predicate[3]) == "string" then
        -- (#eq? @aa "foo")
        str = predicate[3]
      else
        -- (#eq? @aa @bb)
        str = M.get_node_text(match[predicate[3]], source)
      end

      if node_text ~= str or str == nil then
        return false
      end

      return true
  end,

  ["lua-match?"] = function(match, _, source, predicate)
      local node = match[predicate[2]]
      local regex = predicate[3]
      return string.find(M.get_node_text(node, source), regex)
  end,

  ["match?"] = (function()
    local magic_prefixes = {['\\v']=true, ['\\m']=true, ['\\M']=true, ['\\V']=true}
    ---@private
    local function check_magic(str)
      if string.len(str) < 2 or magic_prefixes[string.sub(str,1,2)] then
        return str
      end
      return '\\v'..str
    end

    local compiled_vim_regexes = setmetatable({}, {
      __index = function(t, pattern)
        local res = vim.regex(check_magic(pattern))
        rawset(t, pattern, res)
        return res
      end
    })

    return function(match, _, source, pred)
      local node = match[pred[2]]
      local regex = compiled_vim_regexes[pred[3]]
      return regex:match_str(M.get_node_text(node, source))
    end
  end)(),

  ["contains?"] = function(match, _, source, predicate)
    local node = match[predicate[2]]
    local node_text = M.get_node_text(node, source)

    for i=3,#predicate do
      if string.find(node_text, predicate[i], 1, true) then
        return true
      end
    end

    return false
  end,

  ["any-of?"] = function(match, _, source, predicate)
    local node = match[predicate[2]]
    local node_text = M.get_node_text(node, source)

    -- Since 'predicate' will not be used by callers of this function, use it
    -- to store a string set built from the list of words to check against.
    local string_set = predicate["string_set"]
    if not string_set then
      string_set = {}
      for i=3,#predicate do
        string_set[predicate[i]] = true
      end
      predicate["string_set"] = string_set
    end

    return string_set[node_text]
  end,
}

-- As we provide lua-match? also expose vim-match?
predicate_handlers["vim-match?"] = predicate_handlers["match?"]


-- Directives store metadata or perform side effects against a match.
-- Directives should always end with a `!`.
-- Directive handler receive the following arguments
-- (match, pattern, bufnr, predicate, metadata)
local directive_handlers = {
  ["set!"] = function(_, _, _, pred, metadata)
    if #pred == 4 then
      -- (#set! @capture "key" "value")
      local capture = pred[2]
      if not metadata[capture] then
        metadata[capture] = {}
      end
      metadata[capture][pred[3]] = pred[4]
    else
      -- (#set! "key" "value")
      metadata[pred[2]] = pred[3]
    end
  end,
  -- Shifts the range of a node.
  -- Example: (#offset! @_node 0 1 0 -1)
  ["offset!"] = function(match, _, _, pred, metadata)
    local offset_node = match[pred[2]]
    local range = {offset_node:range()}
    local start_row_offset = pred[3] or 0
    local start_col_offset = pred[4] or 0
    local end_row_offset = pred[5] or 0
    local end_col_offset = pred[6] or 0

    range[1] = range[1] + start_row_offset
    range[2] = range[2] + start_col_offset
    range[3] = range[3] + end_row_offset
    range[4] = range[4] + end_col_offset

    -- If this produces an invalid range, we just skip it.
    if range[1] < range[3] or (range[1] == range[3] and range[2] <= range[4]) then
      metadata.content = {range}
    end
  end
}

--- Adds a new predicate to be used in queries
---
---@param name the name of the predicate, without leading #
---@param handler the handler function to be used
---      signature will be (match, pattern, bufnr, predicate)
function M.add_predicate(name, handler, force)
  if predicate_handlers[name] and not force then
    error(string.format("Overriding %s", name))
  end

  predicate_handlers[name] = handler
end

--- Adds a new directive to be used in queries
---
---@param name the name of the directive, without leading #
---@param handler the handler function to be used
---      signature will be (match, pattern, bufnr, predicate)
function M.add_directive(name, handler, force)
  if directive_handlers[name] and not force then
    error(string.format("Overriding %s", name))
  end

  directive_handlers[name] = handler
end

---@return The list of supported directives.
function M.list_directives()
  return vim.tbl_keys(directive_handlers)
end

---@return The list of supported predicates.
function M.list_predicates()
  return vim.tbl_keys(predicate_handlers)
end

---@private
local function xor(x, y)
  return (x or y) and not (x and y)
end

---@private
local function is_directive(name)
  return string.sub(name, -1) == "!"
end

---@private
function Query:match_preds(match, pattern, source)
  local preds = self.info.patterns[pattern]

  for _, pred in pairs(preds or {}) do
    -- Here we only want to return if a predicate DOES NOT match, and
    -- continue on the other case. This way unknown predicates will not be considered,
    -- which allows some testing and easier user extensibility (#12173).
    -- Also, tree-sitter strips the leading # from predicates for us.
    local pred_name
    local is_not

    -- Skip over directives... they will get processed after all the predicates.
    if not is_directive(pred[1]) then
      if string.sub(pred[1], 1, 4) == "not-" then
        pred_name = string.sub(pred[1], 5)
        is_not = true
      else
        pred_name = pred[1]
        is_not = false
      end

      local handler = predicate_handlers[pred_name]

      if not handler then
        error(string.format("No handler for %s", pred[1]))
        return false
      end

      local pred_matches = handler(match, pattern, source, pred)

      if not xor(is_not, pred_matches) then
        return false
      end
    end
  end
  return true
end

---@private
function Query:apply_directives(match, pattern, source, metadata)
  local preds = self.info.patterns[pattern]

  for _, pred in pairs(preds or {}) do
    if is_directive(pred[1]) then
      local handler = directive_handlers[pred[1]]

      if not handler then
        error(string.format("No handler for %s", pred[1]))
        return
      end

      handler(match, pattern, source, pred, metadata)
    end
  end
end


--- Returns the start and stop value if set else the node's range.
-- When the node's range is used, the stop is incremented by 1
-- to make the search inclusive.
---@private
local function value_or_node_range(start, stop, node)
  if start == nil and stop == nil then
    local node_start, _, node_stop, _ = node:range()
    return node_start, node_stop + 1 -- Make stop inclusive
  end

  return start, stop
end

--- Iterate over all captures from all matches inside {node}
---
--- {source} is needed if the query contains predicates, then the caller
--- must ensure to use a freshly parsed tree consistent with the current
--- text of the buffer (if relevant). {start_row} and {end_row} can be used to limit
--- matches inside a row range (this is typically used with root node
--- as the node, i e to get syntax highlight matches in the current
--- viewport). When omitted the start and end row values are used from the given node.
---
--- The iterator returns three values, a numeric id identifying the capture,
--- the captured node, and metadata from any directives processing the match.
--- The following example shows how to get captures by name:
---
--- <pre>
--- for id, node, metadata in query:iter_captures(tree:root(), bufnr, first, last) do
---   local name = query.captures[id] -- name of the capture in the query
---   -- typically useful info about the node:
---   local type = node:type() -- type of the captured node
---   local row1, col1, row2, col2 = node:range() -- range of the capture
---   ... use the info here ...
--- end
--- </pre>
---
---@param node The node under which the search will occur
---@param source The source buffer or string to extract text from
---@param start The starting line of the search
---@param stop The stopping line of the search (end-exclusive)
---
---@returns The matching capture id
---@returns The captured node
function Query:iter_captures(node, source, start, stop)
  if type(source) == "number" and source == 0 then
    source = vim.api.nvim_get_current_buf()
  end

  start, stop = value_or_node_range(start, stop, node)

  local raw_iter = node:_rawquery(self.query, true, start, stop)
  ---@private
  local function iter()
    local capture, captured_node, match = raw_iter()
    local metadata = {}

    if match ~= nil then
      local active = self:match_preds(match, match.pattern, source)
      match.active = active
      if not active then
        return iter() -- tail call: try next match
      end

      self:apply_directives(match, match.pattern, source, metadata)
    end
    return capture, captured_node, metadata
  end
  return iter
end

--- Iterates the matches of self on a given range.
---
--- Iterate over all matches within a node. The arguments are the same as
--- for |query:iter_captures()| but the iterated values are different:
--- an (1-based) index of the pattern in the query, a table mapping
--- capture indices to nodes, and metadata from any directives processing the match.
--- If the query has more than one pattern the capture table might be sparse,
--- and e.g. `pairs()` method should be used over `ipairs`.
--- Here an example iterating over all captures in every match:
---
--- <pre>
--- for pattern, match, metadata in cquery:iter_matches(tree:root(), bufnr, first, last) do
---   for id, node in pairs(match) do
---     local name = query.captures[id]
---     -- `node` was captured by the `name` capture in the match
---
---     local node_data = metadata[id] -- Node level metadata
---
---     ... use the info here ...
---   end
--- end
--- </pre>
---
---@param node The node under which the search will occur
---@param source The source buffer or string to search
---@param start The starting line of the search
---@param stop The stopping line of the search (end-exclusive)
---
---@returns The matching pattern id
---@returns The matching match
function Query:iter_matches(node, source, start, stop)
  if type(source) == "number" and source == 0 then
    source = vim.api.nvim_get_current_buf()
  end

  start, stop = value_or_node_range(start, stop, node)

  local raw_iter = node:_rawquery(self.query, false, start, stop)
  local function iter()
    local pattern, match = raw_iter()
    local metadata = {}

    if match ~= nil then
      local active = self:match_preds(match, pattern, source)
      if not active then
        return iter() -- tail call: try next match
      end

      self:apply_directives(match, pattern, source, metadata)
    end
    return pattern, match, metadata
  end
  return iter
end

return M