;;; test-wttrin--add-buffer-instructions.el --- Tests for wttrin--add-buffer-instructions -*- lexical-binding: t; -*-

;; Copyright (C) 2024-2026 Craig Jennings

;;; Commentary:
;; Unit tests for wttrin--add-buffer-instructions function.
;; Tests adding user instructions to buffer content.

;;; Code:

(require 'ert)
(require 'wttrin)
(require 'testutil-wttrin)

;;; Setup and Teardown

(defun test-wttrin--expected-footer ()
  "Return the footer string `wttrin--add-buffer-instructions' should produce.
Width 23 is pinned here as a literal, independent of the production
constant, so the test fails if the visible layout drifts."
  (concat "\n\n"
          (format "%-23s%s" "This view" "Saved locations") "\n"
          (format "%-23s%s" "[a] another" "[s] save") "\n"
          (format "%-23s%s" "[g] refresh" "[d] make default") "\n"
          (format "%-23s%s" "[q] quit" "[r] rename") "\n"
          (format "%-23s%s" "" "[x] remove")))

(defun test-wttrin--add-buffer-instructions-setup ()
  "Setup for add-buffer-instructions tests."
  (testutil-wttrin-setup))

(defun test-wttrin--add-buffer-instructions-teardown ()
  "Teardown for add-buffer-instructions tests."
  (testutil-wttrin-teardown))

;;; Normal Cases

(ert-deftest test-wttrin--add-buffer-instructions-normal-empty-buffer-adds-instructions ()
  "Test adding instructions to empty buffer."
  (with-temp-buffer
    (wttrin--add-buffer-instructions)
    (should (string= (test-wttrin--expected-footer)
                     (buffer-string)))))

(ert-deftest test-wttrin--add-buffer-instructions-normal-with-existing-content-appends-instructions ()
  "Test adding instructions to buffer with existing content."
  (with-temp-buffer
    (insert "Weather: Sunny\nTemperature: 20°C")
    (wttrin--add-buffer-instructions)
    (should (string= (concat "Weather: Sunny\nTemperature: 20°C"
                             (test-wttrin--expected-footer))
                     (buffer-string)))))

(ert-deftest test-wttrin--add-buffer-instructions-normal-preserves-point-moves-to-end ()
  "Test that point is moved to end after adding instructions."
  (with-temp-buffer
    (insert "Some content")
    (goto-char (point-min))
    (wttrin--add-buffer-instructions)
    (should (= (point) (point-max)))))

(ert-deftest test-wttrin--add-buffer-instructions-normal-called-twice-adds-instructions-twice ()
  "Test that calling function twice adds instructions twice (not idempotent)."
  (with-temp-buffer
    (insert "Weather")
    (wttrin--add-buffer-instructions)
    (let ((first-result (buffer-string)))
      (wttrin--add-buffer-instructions)
      ;; Should add instructions again, not check if they already exist
      (should-not (string= first-result (buffer-string)))
      ;; Check for two occurrences of the header by counting matches
      (let ((count 0))
        (with-temp-buffer
          (insert first-result)
          (goto-char (point-min))
          (while (search-forward "This view" nil t)
            (setq count (1+ count))))
        ;; After first call, should have 1 occurrence
        (should (= 1 count)))
      ;; After second call, check for 2 occurrences
      (let ((count 0))
        (save-excursion
          (goto-char (point-min))
          (while (search-forward "This view" nil t)
            (setq count (1+ count))))
        (should (= 2 count))))))

(ert-deftest test-wttrin--add-buffer-instructions-normal-key-chords-carry-key-face ()
  "Bracketed key chords are styled with `wttrin-key'."
  (with-temp-buffer
    (wttrin--add-buffer-instructions)
    (goto-char (point-min))
    (search-forward "[a]")
    ;; point is just after the closing bracket; the bracket char is part
    ;; of the "[a]" segment
    (should (eq (get-text-property (1- (point)) 'face) 'wttrin-key))))

(ert-deftest test-wttrin--add-buffer-instructions-normal-prose-carries-instructions-face ()
  "The footer prose is styled with `wttrin-instructions'."
  (with-temp-buffer
    (wttrin--add-buffer-instructions)
    (goto-char (point-min))
    (search-forward "another")
    (should (eq (get-text-property (1- (point)) 'face) 'wttrin-instructions))))

;;; Boundary Cases

(ert-deftest test-wttrin--add-buffer-instructions-boundary-point-at-beginning-appends-at-end ()
  "Test adding instructions when point is at beginning of buffer."
  (with-temp-buffer
    (insert "Weather data here")
    (goto-char (point-min))
    (wttrin--add-buffer-instructions)
    (should (string-suffix-p "[x] remove"
                             (buffer-string)))))

(ert-deftest test-wttrin--add-buffer-instructions-boundary-point-in-middle-appends-at-end ()
  "Test adding instructions when point is in middle of buffer."
  (with-temp-buffer
    (insert "Line 1\nLine 2\nLine 3")
    (goto-char (point-min))
    (forward-line 1)
    (wttrin--add-buffer-instructions)
    (should (string-suffix-p "[x] remove"
                             (buffer-string)))))

(ert-deftest test-wttrin--add-buffer-instructions-boundary-trailing-newlines-preserves-newlines ()
  "Test adding instructions to buffer that already ends with newlines."
  (with-temp-buffer
    (insert "Weather\n\n\n")
    (wttrin--add-buffer-instructions)
    (should (string= (concat "Weather\n\n\n" (test-wttrin--expected-footer))
                     (buffer-string)))))

(ert-deftest test-wttrin--add-buffer-instructions-boundary-very-large-buffer-appends-at-end ()
  "Test adding instructions to large buffer."
  (with-temp-buffer
    (insert (make-string 10000 ?x))
    (wttrin--add-buffer-instructions)
    (goto-char (point-max))
    (should (looking-back "\\[x\\] remove" nil))))

;;; Error Cases

(ert-deftest test-wttrin--add-buffer-instructions-error-read-only-buffer-signals-error ()
  "Test that function signals error when buffer is read-only."
  (with-temp-buffer
    (insert "Some content")
    (read-only-mode 1)
    (should-error (wttrin--add-buffer-instructions)
                  :type 'buffer-read-only)))

(ert-deftest test-wttrin--add-buffer-instructions-error-narrowed-buffer-adds-at-narrowed-end ()
  "Test adding instructions to narrowed buffer adds at narrowed end."
  (with-temp-buffer
    (insert "Line 1\nLine 2\nLine 3\nLine 4")
    (goto-char (point-min))
    (forward-line 1)
    (let ((start (point)))
      (forward-line 1)
      (narrow-to-region start (point))
      (wttrin--add-buffer-instructions)
      ;; Instructions should be added at end of narrowed region
      (widen)
      (goto-char start)
      (forward-line 1)
      (should (looking-at-p "\n\nThis view")))))

(provide 'test-wttrin--add-buffer-instructions)
;;; test-wttrin--add-buffer-instructions.el ends here