-- TODO: remove the end_col field from ContextBounds

--- @class blink.cmp.ContextBounds
--- @field line string
--- @field line_number number
--- @field start_col number
--- @field length number

--- @class blink.cmp.Context
--- @field mode blink.cmp.Mode
--- @field id number
--- @field bufnr number
--- @field cursor number[]
--- @field line string
--- @field bounds blink.cmp.ContextBounds
--- @field trigger blink.cmp.ContextTrigger
--- @field providers string[]
---
--- @field new fun(opts: blink.cmp.ContextOpts): blink.cmp.Context
--- @field get_keyword fun(): string
--- @field within_query_bounds fun(self: blink.cmp.Context, cursor: number[]): boolean
---
--- @field get_mode fun(): blink.cmp.Mode
--- @field get_cursor fun(): number[]
--- @field set_cursor fun(cursor: number[])
--- @field get_line fun(num?: number): string
--- @field get_bounds fun(range: blink.cmp.CompletionKeywordRange): blink.cmp.ContextBounds

--- @class blink.cmp.ContextTrigger
--- @field initial_kind blink.cmp.CompletionTriggerKind The trigger kind when the context was first created
--- @field initial_character? string The trigger character when initial_kind == 'trigger_character'
--- @field kind blink.cmp.CompletionTriggerKind The current trigger kind
--- @field character? string The trigger character when kind == 'trigger_character'

--- @class blink.cmp.ContextOpts
--- @field id number
--- @field providers string[]
--- @field initial_trigger_kind blink.cmp.CompletionTriggerKind
--- @field initial_trigger_character? string
--- @field trigger_kind blink.cmp.CompletionTriggerKind
--- @field trigger_character? string

--- @type blink.cmp.Context
--- @diagnostic disable-next-line: missing-fields
local context = {}

function context.new(opts)
  local cursor = context.get_cursor()
  local line = context.get_line()

  return setmetatable({
    mode = context.get_mode(),
    id = opts.id,
    bufnr = vim.api.nvim_get_current_buf(),
    cursor = cursor,
    line = line,
    bounds = context.get_bounds('full'),
    trigger = {
      initial_kind = opts.initial_trigger_kind,
      initial_character = opts.initial_trigger_character,
      kind = opts.trigger_kind,
      character = opts.trigger_character,
    },
    providers = opts.providers,
  }, { __index = context })
end

function context.get_keyword()
  local keyword = require('blink.cmp.config').completion.keyword
  local range = context.get_bounds(keyword.range)
  return string.sub(context.get_line(), range.start_col, range.start_col + range.length - 1)
end

--- @param cursor number[]
--- @return boolean
function context:within_query_bounds(cursor)
  local row, col = cursor[1], cursor[2]
  local bounds = self.bounds
  return row == bounds.line_number and col >= bounds.start_col and col < (bounds.start_col + bounds.length)
end

function context.get_mode() return vim.api.nvim_get_mode().mode == 'c' and 'cmdline' or 'default' end

function context.get_cursor()
  return context.get_mode() == 'cmdline' and { 1, vim.fn.getcmdpos() - 1 } or vim.api.nvim_win_get_cursor(0)
end

function context.set_cursor(cursor)
  local mode = context.get_mode()
  if mode == 'default' then return vim.api.nvim_win_set_cursor(0, cursor) end

  assert(mode == 'cmdline', 'Unsupported mode for setting cursor: ' .. mode)
  assert(cursor[1] == 1, 'Cursor must be on the first line in cmdline mode')
  vim.fn.setcmdpos(cursor[2])
end

function context.get_line(num)
  if context.get_mode() == 'cmdline' then
    assert(
      num == nil or num == 0,
      'Cannot get line number ' .. tostring(num) .. ' in cmdline mode. Only 0 is supported'
    )
    return vim.fn.getcmdline()
  end

  if num == nil then num = context.get_cursor()[1] - 1 end
  return vim.api.nvim_buf_get_lines(0, num, num + 1, false)[1]
end

--- Gets characters around the cursor and returns the range, 0-indexed
function context.get_bounds(range)
  local line = context.get_line()
  local cursor = context.get_cursor()
  local start_col, end_col = require('blink.cmp.fuzzy').get_keyword_range(line, cursor[2], range)
  return { line_number = cursor[1], start_col = start_col + 1, length = end_col - start_col }
end

return context