select.lua: select from the watch history with g-h

Implement saving watched paths and selecting them.

--osd-playlist-entry determines whether titles and/or filenames are
shown. But unlike in show-text ${playlist} and select-playlist, "file"
and "both" print full paths because history is much more likely to have
files from completely different directories, so showing the directory
conveys where files are located. This is particularly helpful for
filenames like 1.jpg.

The last entry in the selector deletes the history file, as requested by
Samillion.

The history could be formatted as CSV, but this requires escaping the
separator in the fields and doesn't work with paths and titles with
newlines, or as JSON, but it is inefficient to reread and rewrite the
whole history on each new file, and doing so overwrites the history with
an empty file when writing without disk space left. I went with an
hybrid of one JSON array per line to get the best of both worlds. And I
discovered afterwards that this was an existing thing called NDJSON or
JSONL.

DOCS/man/mpv.rst

@@ -328,6 +328,9 @@ g-l
 g-d
     Select an audio device.
 
+g-h
+    Select a file from the watch history. Requires ``--save-watch-history``.
+
 g-w
     Select a file from watch later config files (see `RESUMING PLAYBACK`_) to
     resume playing. Requires ``--write-filename-in-watch-later-config``. This

DOCS/man/options.rst

@@ -1148,6 +1148,17 @@ Watch Later
     Ignore path (i.e. use filename only) when using watch later feature.
     (Default: disabled)
 
+Watch History
+-------------
+
+``--save-watch-history``
+    Whether to save which files are played (default: no). These can be then
+    selected with the default ``g-h`` key binding of select.lua.
+
+``--watch-history-path=<path>``
+    The path in which to store the watch history. Default:
+    ``~~state/watch_history.jsonl`` (see `PATHS`_).
+
 Video
 -----
 

etc/input.conf

@@ -187,6 +187,7 @@
 #g-e script-binding select/select-edition
 #g-l script-binding select/select-subtitle-line
 #g-d script-binding select/select-audio-device
+#g-h script-binding select/select-watch-history
 #g-w script-binding select/select-watch-later
 #g-b script-binding select/select-binding
 #g-r script-binding select/show-properties

options/options.c

@@ -811,6 +811,9 @@ static const m_option_t mp_opts[] = {
     {"watch-later-directory", OPT_ALIAS("watch-later-dir")},
     {"watch-later-options", OPT_STRINGLIST(watch_later_options)},
 
+    {"save-watch-history", OPT_BOOL(save_watch_history)},
+    {"watch-history-path", OPT_STRING(watch_history_path), .flags = M_OPT_FILE},
+
     {"ordered-chapters", OPT_BOOL(ordered_chapters)},
     {"ordered-chapters-files", OPT_STRING(ordered_chapters_files),
         .flags = M_OPT_FILE},
@@ -986,6 +989,7 @@ static const struct MPOpts mp_default_opts = {
     .sync_max_factor = 5,
     .load_config = true,
     .position_resume = true,
+    .watch_history_path = "~~state/watch_history.jsonl",
     .autoload_files = true,
     .demuxer_thread = true,
     .demux_termination_timeout = 0.1,

options/options.h

@@ -276,6 +276,8 @@ typedef struct MPOpts {
     bool ignore_path_in_watch_later_config;
     char *watch_later_dir;
     char **watch_later_options;
+    bool save_watch_history;
+    char *watch_history_path;
     bool pause;
     int keep_open;
     bool keep_open_pause;

player/lua/select.lua

@@ -353,6 +353,113 @@ mp.add_key_binding(nil, "select-audio-device", function ()
     })
 end)
 
+local history_file_path =
+    mp.command_native({"expand-path", mp.get_property("watch-history-path")})
+
+mp.register_event("file-loaded", function ()
+    if not mp.get_property_native("save-watch-history") then
+        return
+    end
+
+    local history_file, error_message = io.open(history_file_path, "a")
+    if not history_file then
+        show_error("Failed to write the watch history: " .. error_message)
+        return
+    end
+
+    local path = mp.command_native({"normalize-path", mp.get_property("path")})
+    local title = mp.get_property("playlist/" .. mp.get_property("playlist-pos") .. "/title")
+
+    history_file:write(utils.format_json({os.time(), path, title}) .. "\n")
+    history_file:close()
+end)
+
+local function add_history_entry(line, items, paths, seen, osd_playlist_entry)
+    local entry = utils.parse_json(line)
+
+    if not entry then
+        mp.msg.warn(line .. " in " .. history_file_path .. " is not valid JSON.")
+        return
+    end
+
+    local time, path, title = unpack(entry)
+
+    if seen[path] then
+        return
+    end
+    seen[path] = true
+
+    local status, date = pcall(os.date, "(%Y-%m-%d %H:%M) ", time)
+
+    if not status or not path then
+        mp.msg.warn(line .. " in " .. history_file_path .. " has invalid data.")
+        return
+    end
+
+    for i, seen_path in ipairs(paths) do
+        if seen_path == path then
+            table.remove(items, i)
+            table.remove(paths, i)
+            break
+        end
+    end
+
+    local item = path
+    if title and osd_playlist_entry == "title" then
+        item = title
+    elseif title and osd_playlist_entry == "both" then
+        item = title .. " (" .. path .. ")"
+    end
+
+    table.insert(items, 1, date .. item)
+    table.insert(paths, 1, path)
+end
+
+mp.add_key_binding(nil, "select-watch-history", function ()
+    local history_file, error_message = io.open(history_file_path)
+    if not history_file then
+        show_warning(mp.get_property_native("save-watch-history")
+                     and error_message
+                     or "Enable --save-watch-history")
+        return
+    end
+
+    local lines = {}
+    local items = {}
+    local paths = {}
+    local seen = {}
+    local osd_playlist_entry = mp.get_property("osd-playlist-entry")
+
+    for line in history_file:lines() do
+        table.insert(lines, line)
+    end
+    history_file:close()
+
+    for i = #lines, 1, -1 do
+        add_history_entry(lines[i], items, paths, seen, osd_playlist_entry)
+    end
+
+    items[#items+1] = "Clear history"
+
+    input.select({
+        prompt = "Select a file:",
+        items = items,
+        submit = function (i)
+            if paths[i] then
+                mp.commandv("loadfile", paths[i])
+                return
+            end
+
+            error_message = select(2, os.remove(history_file_path))
+            if error_message then
+                show_error(error_message)
+            else
+                mp.osd_message("History cleared.")
+            end
+        end,
+    })
+end)
+
 mp.add_key_binding(nil, "select-watch-later", function ()
     local watch_later_dir = mp.get_property("current-watch-later-dir")