local cache = require('cmp.utils.cache')
local char = require('cmp.utils.char')
local misc = require('cmp.utils.misc')
local str = require('cmp.utils.str')
local snippet = require('cmp.utils.snippet')
local config = require('cmp.config')
local types = require('cmp.types')
local matcher = require('cmp.matcher')

---@class cmp.Entry
---@field public id integer
---@field public cache cmp.Cache
---@field public match_cache cmp.Cache
---@field public score integer
---@field public exact boolean
---@field public matches table
---@field public context cmp.Context
---@field public source cmp.Source
---@field public source_offset integer
---@field public source_insert_range lsp.Range
---@field public source_replace_range lsp.Range
---@field public completion_item lsp.CompletionItem
---@field public item_defaults? lsp.internal.CompletionItemDefaults
---@field public resolved_completion_item lsp.CompletionItem|nil
---@field public resolved_callbacks fun()[]
---@field public resolving boolean
---@field public confirmed boolean
---@field public insert_range lsp.Range
---@field public replace_range lsp.Range
---@field public offset integer
---@field public word string
---@field public filter_text string
---@field private match_view_args_ret {input:string, word:string, option:cmp.MatchingConfig, matches:table[]}
local entry = {}
entry.__index = entry

---Create new entry
---@param ctx cmp.Context
---@param source cmp.Source
---@param completion_item lsp.CompletionItem
---@param item_defaults? lsp.internal.CompletionItemDefaults
---@return cmp.Entry
entry.new = function(ctx, source, completion_item, item_defaults)
  local self = setmetatable({}, entry)
  self.id = misc.id('entry.new')
  self.cache = cache.new()
  self.match_cache = cache.new()
  self.score = 0
  self.exact = false
  self.matches = {}
  self.context = ctx
  self.source = source
  self.offset = source.request_offset
  self.source_offset = source.request_offset
  self.source_insert_range = source.default_insert_range
  self.source_replace_range = source.default_replace_range
  self.item_defaults = item_defaults
  self.resolved_completion_item = nil
  self.resolved_callbacks = {}
  self.resolving = false
  self.confirmed = false
  self:_set_completion_item(completion_item)
  return self
end

---@package
entry._set_completion_item = function(self, completion_item)
  if not self.completion_item then
    self.completion_item = self:fill_defaults(completion_item, self.item_defaults)
  else
    -- @see https://github.com/microsoft/vscode/blob/85eea4a9b2ccc99615e970bf2181edbc1781d0f9/src/vs/workbench/api/browser/mainThreadLanguageFeatures.ts#L588
    -- @see https://github.com/microsoft/vscode/blob/85eea4a9b2ccc99615e970bf2181edbc1781d0f9/src/vs/base/common/objects.ts#L89
    -- @see https://github.com/microsoft/vscode/blob/a00f2e64f4fa9a1f774875562e1e9697d7138ed3/src/vs/editor/contrib/suggest/browser/suggest.ts#L147
    for k, v in pairs(completion_item) do
      self.completion_item[k] = v or self.completion_item[k]
    end
  end
  local item = self.completion_item
  ---Create filter text
  self.filter_text = item.filterText or str.trim(item.label)

  -- TODO: the order below is important
  if item.textEdit then
    self.insert_range = self:convert_range_encoding(item.textEdit.insert or item.textEdit.range)
    self.replace_range = self:convert_range_encoding(item.textEdit.replace or item.textEdit.range)
  end

  self.word = self:_get_word()
  self.offset = self:_get_offset()

  if not self.insert_range then
    self.insert_range = {
      start = {
        line = self.context.cursor.row - 1,
        character = self.offset - 1,
      },
      ['end'] = self.source_insert_range['end'],
    }
  end

  if not self.replace_range or ((self.context.cursor.col - 1) == self.replace_range['end'].character) then
    self.replace_range = {
      start = {
        line = self.source_replace_range.start.line,
        character = self.offset - 1,
      },
      ['end'] = self.source_replace_range['end'],
    }
  end
end

---@deprecated use entry.offset instead
entry.get_offset = function(self)
  return self.offset
end

---Make offset value
---@package
---@return integer
entry._get_offset = function(self)
  local offset = self.source_offset
  if self.completion_item.textEdit then
    local range = self.insert_range
    if range then
      local start = math.min(range.start.character + 1, offset)
      for idx = start, self.source_offset do
        local byte = string.byte(self.context.cursor_line, idx)
        if byte == nil or not char.is_white(byte) then
          return idx
        end
      end
      return offset
    end
  else
    -- NOTE
    -- The VSCode does not implement this but it's useful if the server does not care about word patterns.
    -- We should care about this performance.
    local word = self.word
    for idx = self.source_offset - 1, self.source_offset - #word, -1 do
      if char.is_semantic_index(self.context.cursor_line, idx) then
        local c = string.byte(self.context.cursor_line, idx)
        if char.is_white(c) then
          break
        end
        local match = true
        for i = 1, self.source_offset - idx do
          local c1 = string.byte(word, i)
          local c2 = string.byte(self.context.cursor_line, idx + i - 1)
          if not c1 or not c2 or c1 ~= c2 then
            match = false
            break
          end
        end
        if match then
          offset = math.min(offset, idx)
        end
      end
    end
  end
  return offset
end

---@deprecated use entry.word instead
entry.get_word = function(self)
  return self.word
end

---Create word for vim.CompletedItem
---NOTE: This method doesn't clear the cache after completionItem/resolve.
---@package
---@return string
entry._get_word = function(self)
  --NOTE: This is nvim-cmp specific implementation.
  local completion_item = self.completion_item
  if completion_item.word then
    return completion_item.word
  end

  local word
  if completion_item.textEdit and not misc.empty(completion_item.textEdit.newText) then
    word = str.trim(completion_item.textEdit.newText)
    if completion_item.insertTextFormat == types.lsp.InsertTextFormat.Snippet then
      word = tostring(snippet.parse(word))
    end
    local overwrite = self:get_overwrite()
    if 0 < overwrite[2] or completion_item.insertTextFormat == types.lsp.InsertTextFormat.Snippet then
      word = str.get_word(word, string.byte(self.context.cursor_after_line, 1), overwrite[1] or 0)
    end
  elseif not misc.empty(completion_item.insertText) then
    word = str.trim(completion_item.insertText)
    if completion_item.insertTextFormat == types.lsp.InsertTextFormat.Snippet then
      word = str.get_word(tostring(snippet.parse(word)))
    end
  else
    word = str.trim(completion_item.label)
  end
  return str.oneline(word)
end

---Get overwrite information
---@return integer[]
entry.get_overwrite = function(self)
  return self.cache:ensure('get_overwrite', entry._get_overwrite, self)
end

---@package
entry._get_overwrite = function(self)
  if self.completion_item.textEdit then
    local range = self.insert_range
    if range then
      local vim_start = range.start.character + 1
      local vim_end = range['end'].character + 1
      local before = self.context.cursor.col - vim_start
      local after = vim_end - self.context.cursor.col
      return { before, after }
    end
  end
  return { 0, 0 }
end

---@package
entry.get_filter_text = function(self)
  return self.filter_text
end

---Get LSP's insert text
---@return string
entry.get_insert_text = function(self)
  return self.cache:ensure('get_insert_text', entry._get_insert_text, self)
end

---@package
entry._get_insert_text = function(self)
  local completion_item = self.completion_item
  local word
  if completion_item.textEdit then
    word = str.trim(completion_item.textEdit.newText)
    if completion_item.insertTextFormat == types.lsp.InsertTextFormat.Snippet then
      word = str.remove_suffix(str.remove_suffix(word, '$0'), '${0}')
    end
  elseif completion_item.insertText then
    word = str.trim(completion_item.insertText)
    if completion_item.insertTextFormat == types.lsp.InsertTextFormat.Snippet then
      word = str.remove_suffix(str.remove_suffix(word, '$0'), '${0}')
    end
  else
    word = str.trim(completion_item.label)
  end
  return word
end

---Return the item is deprecated or not.
---@return boolean
entry.is_deprecated = function(self)
  return self.completion_item.deprecated or vim.iter(self.completion_item.tags or {}):any(function(...)
    return types.lsp.CompletionItemTag.Deprecated == ...
  end)
end

---Return view information.
---@param suggest_offset integer
---@param entries_buf integer The buffer this entry will be rendered into.
---@return { abbr: { text: string, bytes: integer, width: integer, hl_group: string|table }, kind: { text: string, bytes: integer, width: integer, hl_group: string|table }, menu: { text: string, bytes: integer, width: integer, hl_group: string|table } }
entry.get_view = function(self, suggest_offset, entries_buf)
  local item = self:get_vim_item(suggest_offset)
  return self.cache:ensure('get_view:' .. tostring(entries_buf), entry._get_view, self, item, entries_buf)
end

---@package
entry._get_view = function(self, item, entries_buf)
  local view = {}
  -- The result of vim.fn.strdisplaywidth depends on which buffer it was
  -- called in because it reads the values of the option 'tabstop' when
  -- rendering <Tab> characters.
  vim.api.nvim_buf_call(entries_buf, function()
    view.abbr = {}
    view.abbr.text = item.abbr or ''
    view.abbr.bytes = #view.abbr.text
    view.abbr.width = vim.fn.strdisplaywidth(view.abbr.text)
    view.abbr.hl_group = item.abbr_hl_group or (self:is_deprecated() and 'CmpItemAbbrDeprecated' or 'CmpItemAbbr')
    view.kind = {}
    view.kind.text = item.kind or ''
    view.kind.bytes = #view.kind.text
    view.kind.width = vim.fn.strdisplaywidth(view.kind.text)
    view.kind.hl_group = item.kind_hl_group or ('CmpItemKind' .. (types.lsp.CompletionItemKind[self:get_kind()] or ''))
    view.menu = {}
    view.menu.text = item.menu or ''
    view.menu.bytes = #view.menu.text
    view.menu.width = vim.fn.strdisplaywidth(view.menu.text)
    view.menu.hl_group = item.menu_hl_group or 'CmpItemMenu'
    view.dup = item.dup
  end)

  return view
end

---Make vim.CompletedItem
---@param suggest_offset integer
---@return vim.CompletedItem
entry.get_vim_item = function(self, suggest_offset)
  return self.cache:ensure('get_vim_item:' .. tostring(suggest_offset), entry._get_vim_item, self, suggest_offset)
end

---@package
entry._get_vim_item = function(self, suggest_offset)
  local completion_item = self.completion_item
  local word = self.word
  local abbr = str.oneline(completion_item.label)

  -- ~ indicator
  local is_expandable = false
  local expandable_indicator = config.get().formatting.expandable_indicator
  if #(completion_item.additionalTextEdits or {}) > 0 then
    is_expandable = true
  elseif completion_item.insertTextFormat == types.lsp.InsertTextFormat.Snippet then
    is_expandable = self:get_insert_text() ~= word
  elseif completion_item.kind == types.lsp.CompletionItemKind.Snippet then
    is_expandable = true
  end
  if expandable_indicator and is_expandable then
    abbr = abbr .. '~'
  end

  -- append delta text
  if suggest_offset < self.offset then
    word = string.sub(self.context.cursor_before_line, suggest_offset, self.offset - 1) .. word
  end

  -- labelDetails.
  local menu = nil
  if completion_item.labelDetails then
    menu = ''
    if completion_item.labelDetails.detail then
      menu = menu .. completion_item.labelDetails.detail
    end
    if completion_item.labelDetails.description then
      menu = menu .. completion_item.labelDetails.description
    end
  end

  -- remove duplicated string.
  if self.offset ~= self.context.cursor.col then
    for i = 1, #word do
      if str.has_prefix(self.context.cursor_after_line, string.sub(word, i, #word)) then
        word = string.sub(word, 1, i - 1)
        break
      end
    end
  end

  local cmp_opts = completion_item.cmp or {}

  local vim_item = {
    word = word,
    abbr = abbr,
    kind = cmp_opts.kind_text or types.lsp.CompletionItemKind[self:get_kind()] or types.lsp.CompletionItemKind[1],
    kind_hl_group = cmp_opts.kind_hl_group,
    menu = menu,
    dup = completion_item.dup or 1,
  }
  if config.get().formatting.format then
    vim_item = config.get().formatting.format(self, vim_item)
  end
  vim_item.word = str.oneline(vim_item.word or '')
  vim_item.abbr = str.oneline(vim_item.abbr or '')
  vim_item.kind = str.oneline(vim_item.kind or '')
  vim_item.menu = str.oneline(vim_item.menu or '')
  vim_item.equal = 1
  vim_item.empty = 1

  return vim_item
end

---Get commit characters
---@return string[]
entry.get_commit_characters = function(self)
  return self.completion_item.commitCharacters or {}
end

---@deprecated use entry.insert_range instead
entry.get_insert_range = function(self)
  return self.insert_range
end

---@deprecated use entry.replace_range instead
entry.get_replace_range = function(self)
  return self.replace_range
end

---Match line.
---@param input string
---@param matching_config cmp.MatchingConfig
---@return { score: integer, matches: table[] }
entry.match = function(self, input, matching_config)
  -- https://www.lua.org/pil/11.6.html
  -- do not use '..' to allocate multiple strings
  local cache_key = string.format('%s:%d:%d:%d:%d:%d:%d', input, self.resolved_completion_item and 1 or 0, matching_config.disallow_fuzzy_matching and 1 or 0, matching_config.disallow_partial_matching and 1 or 0, matching_config.disallow_prefix_unmatching and 1 or 0, matching_config.disallow_partial_fuzzy_matching and 1 or 0, matching_config.disallow_symbol_nonprefix_matching and 1 or 0)
  local matched = self.match_cache:get(cache_key)
  if matched then
    if self.match_view_args_ret and self.match_view_args_ret.input ~= input then
      self.match_view_args_ret.input = input
      self.match_view_args_ret.word = matched._word
      self.match_view_args_ret.matches = matched.matches
    end
    return matched
  end
  matched = self:_match(input, matching_config)
  self.match_cache:set(cache_key, matched)
  return matched
end

---@package
entry._match = function(self, input, matching_config)
  local completion_item = self.completion_item
  local option = {
    disallow_fuzzy_matching = matching_config.disallow_fuzzy_matching,
    disallow_partial_fuzzy_matching = matching_config.disallow_partial_fuzzy_matching,
    disallow_partial_matching = matching_config.disallow_partial_matching,
    disallow_prefix_unmatching = matching_config.disallow_prefix_unmatching,
    disallow_symbol_nonprefix_matching = matching_config.disallow_symbol_nonprefix_matching,
    synonyms = {
      self.word,
      self.completion_item.label,
    },
  }

  local score, matches, filter_text
  local checked = {} ---@type table<string, boolean>

  filter_text = self.filter_text
  checked[filter_text] = true
  score, matches = matcher.match(input, filter_text, option)

  -- Support the language server that doesn't respect VSCode's behaviors.
  if score == 0 then
    if completion_item.textEdit and not misc.empty(completion_item.textEdit.newText) then
      local diff = self.source_offset - self.offset
      if diff > 0 then
        local prefix = string.sub(self.context.cursor_line, self.offset, self.offset + diff)
        local accept = nil
        accept = accept or string.match(prefix, '^[^%a]+$')
        accept = accept or string.find(completion_item.textEdit.newText, prefix, 1, true)
        if accept then
          filter_text = prefix .. filter_text
          if not checked[filter_text] then
            checked[filter_text] = true
            score, matches = matcher.match(input, filter_text, option)
          end
        end
      end
    end
  end

  -- Fix highlight if filterText is not the same to vim_item.abbr.
  if score > 0 then
    self.match_view_args_ret = {
      input = input,
      word = filter_text,
      option = option,
      matches = matches,
    }
  end

  return { score = score, matches = matches, _word = filter_text }
end

---@param view string
entry.get_view_matches = function(self, view)
  if self.match_view_args_ret then
    if self.match_view_args_ret.word == view then
      return self.match_view_args_ret.matches
    end
    self.match_view_args_ret.word = view
    local input = self.match_view_args_ret.input
    local diff = self.source_offset - self.offset
    if diff > 0 then
      input = input:sub(1 + diff)
    end
    local _, matches = matcher.match(input, view, self.match_view_args_ret.option)
    self.match_view_args_ret.matches = matches
    return matches
  end
end

---@deprecated use entry.completion_item instead
entry.get_completion_item = function(self)
  return self.completion_item
end

---Create documentation
---@return string[]
entry.get_documentation = function(self)
  local item = self.completion_item
  local documents = {}

  if type(item.detail) == 'table' then
    item.detail = item.detail[1]
  end

  -- detail
  if item.detail and item.detail ~= '' then
    local ft = self.context.filetype
    local dot_index = string.find(ft, '%.')
    if dot_index ~= nil then
      ft = string.sub(ft, 0, dot_index - 1)
    end
    table.insert(documents, {
      kind = types.lsp.MarkupKind.Markdown,
      value = ('```%s\n%s\n```'):format(ft, str.trim(item.detail)),
    })
  end

  local documentation = item.documentation
  if type(documentation) == 'string' and documentation ~= '' then
    local value = str.trim(documentation)
    if value ~= '' then
      table.insert(documents, {
        kind = types.lsp.MarkupKind.PlainText,
        value = value,
      })
    end
  elseif type(documentation) == 'table' and not misc.empty(documentation.value) then
    local value = str.trim(documentation.value)
    if value ~= '' then
      table.insert(documents, {
        kind = documentation.kind,
        value = value,
      })
    end
  end

  return vim.lsp.util.convert_input_to_markdown_lines(documents)
end

---Get completion item kind
---@return lsp.CompletionItemKind
entry.get_kind = function(self)
  return self.completion_item.kind or types.lsp.CompletionItemKind.Text
end

---Execute completion item's command.
---@param callback fun()
entry.execute = function(self, callback)
  self.source:execute(self.completion_item, callback)
end

---Resolve completion item.
---@param callback fun()
entry.resolve = function(self, callback)
  if self.resolved_completion_item then
    return callback()
  end
  table.insert(self.resolved_callbacks, callback)

  if not self.resolving then
    self.resolving = true
    self.source:resolve(self.completion_item, function(completion_item)
      self.resolving = false
      if not completion_item then
        return
      end
      self:_set_completion_item(completion_item)
      self.resolved_completion_item = self.completion_item
      self.cache:clear()
      for _, c in ipairs(self.resolved_callbacks) do
        c()
      end
    end)
  end
end

---@param completion_item lsp.CompletionItem
---@param defaults? lsp.internal.CompletionItemDefaults
---@return lsp.CompletionItem
entry.fill_defaults = function(_, completion_item, defaults)
  defaults = defaults or {}

  if defaults.data then
    completion_item.data = completion_item.data or defaults.data
  end

  if defaults.commitCharacters then
    completion_item.commitCharacters = completion_item.commitCharacters or defaults.commitCharacters
  end

  if defaults.insertTextFormat then
    completion_item.insertTextFormat = completion_item.insertTextFormat or defaults.insertTextFormat
  end

  if defaults.insertTextMode then
    completion_item.insertTextMode = completion_item.insertTextMode or defaults.insertTextMode
  end

  if defaults.editRange then
    if not completion_item.textEdit then
      if defaults.editRange.insert then
        completion_item.textEdit = {
          insert = defaults.editRange.insert,
          replace = defaults.editRange.replace,
          newText = completion_item.textEditText or completion_item.label,
        }
      else
        completion_item.textEdit = {
          range = defaults.editRange, --[[@as lsp.Range]]
          newText = completion_item.textEditText or completion_item.label,
        }
      end
    end
  end

  return completion_item
end

---Convert the oneline range encoding.
entry.convert_range_encoding = function(self, range)
  local from_encoding = self.source.position_encoding
  local cache_key = string.format('entry.convert_range_encoding:%d:%d:%s', range.start.character, range['end'].character, from_encoding)
  local res = self.context.cache:get(cache_key)
  if res then
    return res
  end
  res = {
    start = types.lsp.Position.to_utf8(self.context.cursor_line, range.start, from_encoding),
    ['end'] = types.lsp.Position.to_utf8(self.context.cursor_line, range['end'], from_encoding),
  }
  self.context.cache:set(cache_key, res)
  return res
end

---Return true if the entry is invalid.
entry.is_invalid = function(self)
  local is_invalid = false
  is_invalid = is_invalid or misc.empty(self.completion_item.label)
  if self.completion_item.textEdit then
    local range = self.completion_item.textEdit.range or self.completion_item.textEdit.insert
    is_invalid = is_invalid or range.start.line ~= range['end'].line or range.start.line ~= self.context.cursor.line
  end
  return is_invalid
end

return entry
