local api = vim.api
local query = vim.treesitter.query
local Range = require('vim.treesitter._range')

local ns = api.nvim_create_namespace('nvim.treesitter.highlighter')

---@alias vim.treesitter.highlighter.Iter fun(end_line: integer|nil): integer, TSNode, vim.treesitter.query.TSMetadata, TSQueryMatch

---@class (private) vim.treesitter.highlighter.Query
---@field private _query vim.treesitter.Query?
---@field private lang string
---@field private hl_cache table<integer,integer>
local TSHighlighterQuery = {}
TSHighlighterQuery.__index = TSHighlighterQuery

---@private
---@param lang string
---@param query_string string?
---@return vim.treesitter.highlighter.Query
function TSHighlighterQuery.new(lang, query_string)
  local self = setmetatable({}, TSHighlighterQuery)
  self.lang = lang
  self.hl_cache = {}

  if query_string then
    self._query = query.parse(lang, query_string)
  else
    self._query = query.get(lang, 'highlights')
  end

  return self
end

---@package
---@param capture integer
---@return integer?
function TSHighlighterQuery:get_hl_from_capture(capture)
  if not self.hl_cache[capture] then
    local name = self._query.captures[capture]
    local id = 0
    if not vim.startswith(name, '_') then
      id = api.nvim_get_hl_id_by_name('@' .. name .. '.' .. self.lang)
    end
    self.hl_cache[capture] = id
  end

  return self.hl_cache[capture]
end

---@nodoc
function TSHighlighterQuery:query()
  return self._query
end

---@class (private) vim.treesitter.highlighter.State
---@field tstree TSTree
---@field next_row integer
---@field iter vim.treesitter.highlighter.Iter?
---@field highlighter_query vim.treesitter.highlighter.Query

---@nodoc
---@class vim.treesitter.highlighter
---@field active table<integer,vim.treesitter.highlighter>
---@field bufnr integer
---@field private orig_spelloptions string
--- A map of highlight states.
--- This state is kept during rendering across each line update.
---@field private _highlight_states vim.treesitter.highlighter.State[]
---@field private _queries table<string,vim.treesitter.highlighter.Query>
---@field  _conceal_line boolean?
---@field  _conceal_checked table<integer, boolean>
---@field tree vim.treesitter.LanguageTree
---@field private redraw_count integer
---@field parsing boolean true if we are parsing asynchronously
local TSHighlighter = {
  active = {},
}

TSHighlighter.__index = TSHighlighter

---@nodoc
---
--- Creates a highlighter for `tree`.
---
---@param tree vim.treesitter.LanguageTree parser object to use for highlighting
---@param opts (table|nil) Configuration of the highlighter:
---           - queries table overwrite queries used by the highlighter
---@return vim.treesitter.highlighter Created highlighter object
function TSHighlighter.new(tree, opts)
  local self = setmetatable({}, TSHighlighter)

  if type(tree:source()) ~= 'number' then
    error('TSHighlighter can not be used with a string parser source.')
  end

  opts = opts or {} ---@type { queries: table<string,string> }
  self.tree = tree
  tree:register_cbs({
    on_detach = function()
      self:on_detach()
    end,
  })

  -- Enable conceal_lines if query exists for lang and has conceal_lines metadata.
  local function set_conceal_lines(lang)
    if not self._conceal_line and self:get_query(lang):query() then
      self._conceal_line = self:get_query(lang):query().has_conceal_line
    end
  end

  tree:register_cbs({
    on_changedtree = function(...)
      self:on_changedtree(...)
    end,
    on_child_removed = function(child)
      child:for_each_tree(function(t)
        self:on_changedtree(t:included_ranges(true))
      end)
    end,
    on_child_added = function(child)
      child:for_each_tree(function(t)
        set_conceal_lines(t:lang())
      end)
    end,
  }, true)

  local source = tree:source()
  assert(type(source) == 'number')

  self.bufnr = source
  self.redraw_count = 0
  self._conceal_checked = {}
  self._queries = {}

  -- Queries for a specific language can be overridden by a custom
  -- string query... if one is not provided it will be looked up by file.
  if opts.queries then
    for lang, query_string in pairs(opts.queries) do
      self._queries[lang] = TSHighlighterQuery.new(lang, query_string)
      set_conceal_lines(lang)
    end
  end
  set_conceal_lines(tree:lang())
  self.orig_spelloptions = vim.bo[self.bufnr].spelloptions

  vim.bo[self.bufnr].syntax = ''
  vim.b[self.bufnr].ts_highlight = true

  TSHighlighter.active[self.bufnr] = self

  -- Tricky: if syntax hasn't been enabled, we need to reload color scheme
  -- but use synload.vim rather than syntax.vim to not enable
  -- syntax FileType autocmds. Later on we should integrate with the
  -- `:syntax` and `set syntax=...` machinery properly.
  -- Still need to ensure that syntaxset augroup exists, so that calling :destroy()
  -- immediately afterwards will not error.
  if vim.g.syntax_on ~= 1 then
    vim.cmd.runtime({ 'syntax/synload.vim', bang = true })
    api.nvim_create_augroup('syntaxset', { clear = false })
  end

  vim._with({ buf = self.bufnr }, function()
    vim.opt_local.spelloptions:append('noplainbuffer')
  end)

  return self
end

--- @nodoc
--- Removes all internal references to the highlighter
function TSHighlighter:destroy()
  TSHighlighter.active[self.bufnr] = nil

  if api.nvim_buf_is_loaded(self.bufnr) then
    vim.bo[self.bufnr].spelloptions = self.orig_spelloptions
    vim.b[self.bufnr].ts_highlight = nil
    api.nvim_buf_clear_namespace(self.bufnr, ns, 0, -1)
    if vim.g.syntax_on == 1 then
      api.nvim_exec_autocmds(
        'FileType',
        { group = 'syntaxset', buffer = self.bufnr, modeline = false }
      )
    end
  end
end

---@param srow integer
---@param erow integer exclusive
---@private
function TSHighlighter:prepare_highlight_states(srow, erow)
  self._highlight_states = {}

  self.tree:for_each_tree(function(tstree, tree)
    if not tstree then
      return
    end

    local root_node = tstree:root()
    local root_start_row, _, root_end_row, _ = root_node:range()

    -- Only consider trees within the visible range
    if root_start_row > erow or root_end_row < srow then
      return
    end

    local hl_query = self:get_query(tree:lang())
    -- Some injected languages may not have highlight queries.
    if not hl_query:query() then
      return
    end

    -- _highlight_states should be a list so that the highlights are added in the same order as
    -- for_each_tree traversal. This ensures that parents' highlight don't override children's.
    table.insert(self._highlight_states, {
      tstree = tstree,
      next_row = 0,
      iter = nil,
      highlighter_query = hl_query,
    })
  end)
end

---@param fn fun(state: vim.treesitter.highlighter.State)
---@package
function TSHighlighter:for_each_highlight_state(fn)
  for _, state in ipairs(self._highlight_states) do
    fn(state)
  end
end

---@package
function TSHighlighter:on_detach()
  self:destroy()
end

---@package
---@param changes Range6[]
function TSHighlighter:on_changedtree(changes)
  for _, ch in ipairs(changes) do
    api.nvim__redraw({ buf = self.bufnr, range = { ch[1], ch[4] + 1 }, flush = false })
    -- Only invalidate the _conceal_checked range if _conceal_line is set and
    -- ch[4] is not UINT32_MAX (empty range on first changedtree).
    if ch[4] == 2 ^ 32 - 1 then
      self._conceal_checked = {}
    end
    for i = ch[1], self._conceal_line and ch[4] ~= 2 ^ 32 - 1 and ch[4] or 0 do
      self._conceal_checked[i] = false
    end
  end
end

--- Gets the query used for @param lang
---@nodoc
---@param lang string Language used by the highlighter.
---@return vim.treesitter.highlighter.Query
function TSHighlighter:get_query(lang)
  if not self._queries[lang] then
    local success, result = pcall(TSHighlighterQuery.new, lang)
    if not success then
      self:destroy()
      error(result)
    end
    self._queries[lang] = result
  end

  return self._queries[lang]
end

--- @param match TSQueryMatch
--- @param bufnr integer
--- @param capture integer
--- @param metadata vim.treesitter.query.TSMetadata
--- @return string?
local function get_url(match, bufnr, capture, metadata)
  ---@type string|number|nil
  local url = metadata[capture] and metadata[capture].url

  if not url or type(url) == 'string' then
    return url
  end

  local captures = match:captures()

  if not captures[url] then
    return
  end

  -- Assume there is only one matching node. If there is more than one, take the URL
  -- from the first.
  local other_node = captures[url][1]

  return vim.treesitter.get_node_text(other_node, bufnr, {
    metadata = metadata[url],
  })
end

--- @param capture_name string
--- @return boolean?, integer
local function get_spell(capture_name)
  if capture_name == 'spell' then
    return true, 0
  elseif capture_name == 'nospell' then
    -- Give nospell a higher priority so it always overrides spell captures.
    return false, 1
  end
  return nil, 0
end

---@param self vim.treesitter.highlighter
---@param buf integer
---@param line integer
---@param on_spell boolean
---@param on_conceal boolean
local function on_line_impl(self, buf, line, on_spell, on_conceal)
  self._conceal_checked[line] = true
  self:for_each_highlight_state(function(state)
    local root_node = state.tstree:root()
    local root_start_row, _, root_end_row, _ = root_node:range()

    -- Only consider trees that contain this line
    if root_start_row > line or root_end_row < line then
      return
    end

    local tree_region = state.tstree:included_ranges(true)

    if state.iter == nil or state.next_row < line then
      -- Mainly used to skip over folds

      -- TODO(lewis6991): Creating a new iterator loses the cached predicate results for query
      -- matches. Move this logic inside iter_captures() so we can maintain the cache.
      state.iter =
        state.highlighter_query:query():iter_captures(root_node, self.bufnr, line, root_end_row + 1)
    end

    local captures = state.highlighter_query:query().captures

    while line >= state.next_row do
      local capture, node, metadata, match = state.iter(line)

      local outer_range = { root_end_row + 1, 0, root_end_row + 1, 0 }
      if node then
        outer_range = vim.treesitter.get_range(node, buf, metadata and metadata[capture])
      end
      local outer_range_start_row = outer_range[1]

      for _, range in ipairs(tree_region) do
        local intersection = Range.intersection(range, outer_range)
        if intersection then
          local start_row, start_col, end_row, end_col = Range.unpack4(intersection)

          if capture then
            local hl = state.highlighter_query:get_hl_from_capture(capture)

            local capture_name = captures[capture]

            local spell, spell_pri_offset = get_spell(capture_name)

            -- The "priority" attribute can be set at the pattern level or on a particular capture
            local priority = (
              tonumber(metadata.priority or metadata[capture] and metadata[capture].priority)
              or vim.hl.priorities.treesitter
            ) + spell_pri_offset

            -- The "conceal" attribute can be set at the pattern level or on a particular capture
            local conceal = metadata.conceal or metadata[capture] and metadata[capture].conceal

            local url = get_url(match, buf, capture, metadata)

            if hl and end_row >= line and not on_conceal and (not on_spell or spell ~= nil) then
              api.nvim_buf_set_extmark(buf, ns, start_row, start_col, {
                end_line = end_row,
                end_col = end_col,
                hl_group = hl,
                ephemeral = true,
                priority = priority,
                conceal = conceal,
                spell = spell,
                url = url,
              })
            end

            if
              (metadata.conceal_lines or metadata[capture] and metadata[capture].conceal_lines)
              and #api.nvim_buf_get_extmarks(buf, ns, { start_row, 0 }, { start_row, 0 }, {}) == 0
            then
              api.nvim_buf_set_extmark(buf, ns, start_row, 0, {
                end_line = end_row,
                conceal_lines = '',
              })
            end
          end
        end
      end

      if outer_range_start_row > line then
        state.next_row = outer_range_start_row
      end
    end
  end)
end

---@private
---@param _win integer
---@param buf integer
---@param line integer
function TSHighlighter._on_line(_, _win, buf, line, _)
  local self = TSHighlighter.active[buf]
  if not self then
    return
  end

  on_line_impl(self, buf, line, false, false)
end

---@private
---@param buf integer
---@param srow integer
---@param erow integer
function TSHighlighter._on_spell_nav(_, _, buf, srow, _, erow, _)
  local self = TSHighlighter.active[buf]
  if not self then
    return
  end

  -- Do not affect potentially populated highlight state. Here we just want a temporary
  -- empty state so the C code can detect whether the region should be spell checked.
  local highlight_states = self._highlight_states
  self:prepare_highlight_states(srow, erow)

  for row = srow, erow do
    on_line_impl(self, buf, row, true, false)
  end
  self._highlight_states = highlight_states
end

---@private
---@param buf integer
---@param row integer
function TSHighlighter._on_conceal_line(_, _, buf, row)
  local self = TSHighlighter.active[buf]
  if not self or not self._conceal_line or self._conceal_checked[row] then
    return
  end

  -- Do not affect potentially populated highlight state.
  local highlight_states = self._highlight_states
  self.tree:parse({ row, row })
  self:prepare_highlight_states(row, row)
  on_line_impl(self, buf, row, false, true)
  self._highlight_states = highlight_states
end

---@private
--- Clear conceal_lines marks whenever we redraw for a buffer change. Marks are
--- added back as either the _conceal_line or on_win callback comes across them.
function TSHighlighter._on_buf(_, buf)
  local self = TSHighlighter.active[buf]
  if not self or not self._conceal_line then
    return
  end

  api.nvim_buf_clear_namespace(buf, ns, 0, -1)
  self._conceal_checked = {}
end

---@private
---@param buf integer
---@param topline integer
---@param botline integer
function TSHighlighter._on_win(_, _, buf, topline, botline)
  local self = TSHighlighter.active[buf]
  if not self or self.parsing then
    return false
  end
  self.parsing = self.tree:parse({ topline, botline + 1 }, function(_, trees)
    if trees and self.parsing then
      self.parsing = false
      api.nvim__redraw({ buf = buf, valid = false, flush = false })
    end
  end) == nil
  self.redraw_count = self.redraw_count + 1
  self:prepare_highlight_states(topline, botline)
  return #self._highlight_states > 0
end

api.nvim_set_decoration_provider(ns, {
  on_win = TSHighlighter._on_win,
  on_line = TSHighlighter._on_line,
  on_buf = TSHighlighter._on_buf,
  _on_spell_nav = TSHighlighter._on_spell_nav,
  _on_conceal_line = TSHighlighter._on_conceal_line,
})

return TSHighlighter
