local util = require("jjannotate.util")

local M = {}

---@class jjannotate.Range
---@field start integer 0-indexed inclusive
---@field _end integer 0-indexed inclusive

---@class jjannotate.Line
---@field range jjannotate.Range
---@field change_id string
---@field author string
---@field timestamp string

---@class jjannotate.AnnotateResult
---@field lines jjannotate.Line[]
---@field longest_timestamp integer
---@field row_index jjannotate.Line[]
---@field change_id_index table<string, jjannotate.Line[]>

--- A version control backend. Every backend annotation resolves a `revision`
--- to a canonical revision ID and annotates/reads files at it.
---@class jjannotate.Backend
---@field name string backend name, e.g. "jj" or "git"
---@field marker string root marker used to detect the backend, e.g. ".jj" or ".git"
---@field annotate fun(repo: string, path: string, revision: string, cb: fun(result: jjannotate.AnnotateResult?))
---@field show fun(repo: string, revision: string)
---@field file_contents fun(repo: string, path: string, revision: string, cb: fun(contents: string?))
---@field resolve_revision fun(repo: string, revision: string?, cb?: fun(id: string?)): string?

---@class jjannotate.RepoInfo
---@field backend jjannotate.Backend
---@field repo string repo root
---@field path string path within `repo`

--- Backends in detection priority order.
---@type jjannotate.Backend[]
M.backends = { require("jjannotate.backend.jj"), require("jjannotate.backend.git") }

--- Resolves the given `path`'s backend, repo root, and relative path within the repo.
--- Returns `nil` if `path` is not in any supported repo.
---@param path string
---@return jjannotate.RepoInfo?
function M.path_info(path)
  if path == "" then return nil end

  path = vim.fs.normalize(vim.fs.abspath(path))

  for _, backend in ipairs(M.backends) do
    local repo = vim.fs.root(path, backend.marker)
    if repo then
      local relpath = vim.fs.relpath(repo, path)
      if relpath then return { backend = backend, repo = repo, path = relpath } end
    end
  end
end

--- Resolves the given `buf`'s backend, repo root, and relative path within the repo.
--- Handles annotate URI buffers, falling back to filesystem detection.
--- Returns `nil` if the buffer is not in any supported repo.
---@param buf integer
---@return jjannotate.RepoInfo?
function M.buf_info(buf)
  local ref = util.parse_uri("annotate", vim.api.nvim_buf_get_name(buf))
  if ref then
    local info = M.path_info(ref.repo)
    if info then return { backend = info.backend, repo = ref.repo, path = ref.path } end
  end

  return M.path_info(vim.api.nvim_buf_get_name(buf))
end

--- Detects the backend for the given path (or repo root).
---@param path string
---@return jjannotate.Backend?
function M.detect(path)
  local info = M.path_info(path)
  if not info then
    util.notify(string.format("`%s` is not in a jj or git repo", path), vim.log.levels.ERROR)
    return
  end
  return info.backend
end

return M