-- Show OSD stream title from playlist on change
--
-- Usefull for iPTV when switching the streams/channels defined in the playlist
--
-- At the moment of jump from stream1 to stream2 the property 'media-title' still contains stream1.title
-- (see mpv doc for more details, lookup playlist/N/current, playlist/N/playing )
-- To display correct stream2.title from playlist use this script.
--
-- Note: Optional stream specific mpv properties can be set in the second comma separated section.
-- For example to activate subtitles id 1 and audio id 2 for "Film Europe" use playlist line:
-- #EXTINF:0,Film Europe,sid="1" aid="3",0
--
-- Note: 'force-media-title' property get updated also with empty value so
-- testing for empty value is required before formatting and OSDing
--
-- Note: 'media-title' property gets updated more often then switching channels.
-- Therefore the script has to validate the 'media-title', It is omplemented
-- by 'media-title' matching to cfg.valid pattern. The empty cfg.valid activates
-- 'passthrough' mode (all 'media-title' changes are valid and shown). The default
-- cfg.valid pattern should be OK, actually is based on SMPlayer formatted playlist
--
-- To customize configuration place show-stream-title.conf template into
-- dir ~/.config/mpv/script-opts/ [~/.config/mpv/lua-settings/] and edit
--
-- Place script into ~/.config/mpv/scripts/ for autoload
--
-- OSD options like duration, alignment, border, scale could be set in ~/.config/mpv/mpv.conf
--
-- SMPlayer playlist entry example:
--   #EXTINF:0,RT News,,0
--   http://rt-eng-live.hls.adaptive.level3.net/rt/eng/index1600.m3u8
--
-- GitHub: https://github.com/blue-sky-r/mpv/tree/master/scripts

-- OSD format string tokens:
-- %N ... iPTV channel number (playlist index 1-based)
-- %t ... iPTV channel name (user friendly stream title)
-- %T ... iPTV channel name in uppercase

local options = require("mp.options")
local utils = require("mp.utils")

-- defaults
local cfg = {
    -- OSD text format
    format = "%N. %t",
    -- validate title from playlist (empty for passthrough = valid all)
    valid  = "^.+,.*,0$",
    -- ignore title matching filename property
    ignorefilename = true
}

-- read lua-settings/show-stream-title.conf
options.read_options(cfg, 'show-stream-title')

-- log active config
mp.msg.verbose('cfg = '.. utils.to_string(cfg))

-- string v is empty
local function empty(v)
    return not v or v == '' or string.find(v, "^%s*$")
end

-- key,val iterator from string key1="val1" key2="val2"
local function key_val_iter(s)
    -- start idx
    local idx = 0
    -- closure
    return function()
        -- extract key,val from string key="val"
        _, idx, key, val = string.find(s, '([%w-]+)="([^"]+)"', idx)
        -- return found key/val
        if idx then
            mp.msg.verbose("found key(".. key ..") = val(".. val ..") at idx:".. idx)
            return key, val
        end
    end
end

-- check if string is valid title by cfg.valid pattern
-- valid:   'CP24,,0', 'TA News,,0'
-- invalid: 'index', 'DVR', 'iptv-streams.m3u8', 'rtmp://ip'
local function is_valid_title(s)
    -- everything is valid (passthrough) if validation pattern is missing
    if not cfg.valid then return true end
    -- empty (nil) is invalid
    if empty(s) then return false end
    -- validate with pattern
    return string.match(s, cfg.valid)
end

-- [show_stream_title] property 'media-title' changed to 'iptv-streams.m3u8'
-- [show_stream_title] property 'media-title' changed to 'CP24,,0'
--
-- [show_stream_title] property 'media-title' changed to 'TA News,,0'
-- [show_stream_title] property 'media-title' changed to 'rtmp://eo1-gts.ta.live.cc:1945/ta-o/_definst_/livem2'
--
-- [show_stream_title] property 'media-title' changed to 'EDU,:/default-theme/openfolder.png,1'
-- [show_stream_title] property 'media-title' changed to 'History,,0'
--
-- [cplayer] Set property: file-local-options/force-media-title="index" -> 1
-- [show_stream_title] property 'media-title' changed to 'index'
--

-- format and show OSD forced media title val if not empty
local function force_media_title(name, val)
    -- currently played filename
    local filename = mp.get_property('filename/no-ext', '')
    -- log
    mp.msg.info("force_media_title(name:".. name ..", val:".. val ..") filename:".. filename)
    -- val can be empty
    if empty(val) then return end

    -- optional ignore filename
    if cfg.ignorefilename and filename:find(val, 1, true) == 1 then return end

    -- playlist index (1-based)
    local n = mp.get_property('playlist-pos-1')
    -- replace tokens
    local txt = string.gsub(cfg.format, '%%N', n):gsub('%%t', val):gsub('%%T', string.upper(val))

    -- osd show
    mp.osd_message(txt)
end

-- pass as force media title if media title val is valid
local function media_title(name, val)
    -- log
    mp.msg.info("media_title(name:".. name ..", val:".. utils.to_string(val) ..")")
    -- val can be url (redirects ?)
    if not is_valid_title(val) then return end

    -- SMPlayer playlist val = 'Title,,0'
    --          playlist val = 'Title'

    -- set custom stream options
    for pname,pval in key_val_iter(val) do
        mp.msg.info("set_property(".. pname ..", ".. pval ..")")
        mp.set_property(pname, pval)
    end

    -- get comma position or entire length
    local compos = string.find(val ..",", ",")
    -- strip commas from stream title
    local title = string.sub(val, 1, compos - 1)
    -- osd
    force_media_title(name, title)
end

-- observe media-title
mp.observe_property("media-title", "string", media_title)

-- observe force-meduia-title
mp.observe_property("force-media-title", "string", force_media_title)