-- take str, delete all chars between
-- indices i0 and i1 (inclusive), and
-- insert newstr into that space
local function splice(str,i0,i1, newstr)
    return sub(str,1,max(1,i0)-1)..(newstr or "")..sub(str,i1+1)
end

-- use str:find to do sed-like file editing.
-- no lua patterns, just literal string matching
-- return str, but replace the first instance of cut with paste
local function _replace(str,cut,paste)
    local i0,i1 = str:find(cut,1,true) -- no pattern-matching
    if not i0 then
        return str,false
    end
    return splice(str,i0,i1,paste),true
end

local function sedish(fname,mods)
    local src = fetch(fname)
    if not src then
        printh("sedish: couldn't find file "..fname)
        return
    end

    for i,mod in ipairs(mods) do
        local cut,paste = unpack(mod)
        -- printh(cut.." "..paste)
        if not cut or not paste then
            printh("sedish: bad cut/paste data in "..fname)
            return
        end
        local changed
        src,changed = _replace(src,cut,paste)
        if not changed then
            printh("sedish: mod #"..i.." did nothing to "..fname)
        end
        if not src or #src==0 then
            printh("sedish: bad result in "..fname)
            return
        end
    end
    -- printh("storing "..fname..": "..sub(src,1,100):gsub("[\n\r]",""))
    store(fname,src)
end

sedish("/system/lib/gui_ed.lua",{
    { -- fix alt-tab annoyance (pressing alt-tab inserts tab character into code)
        [[if (keyp("tab")) then]],
        [[if keyp"tab" and not key"alt" then]],
    },
})

sedish("/system/apps/podtree.p64/main.lua",{
    { -- fix podtree bug (pressing enter crashes the program)
        [[if(key("shift")) return true]],
        [[if(_ENV.key("shift")) return true]],
    },
})

-- (you need to open a new gfx tab for these gfx.p64 edits to work)
sedish("/system/apps/gfx.p64/pal.lua",{
    { -- show pal numbers
        [[pcols[x + y*epr])]],
        [[pcols[x + y*epr])if pal_swatch==1 and x%2==0 then print(pcols[x + y*epr],x*ww+5,y*ww+1,0) end]],
    },
})
-- sedish("/system/apps/gfx.p64/nav.lua",{
--  { -- display sprite numbers in hex
--      [[string.format("%03d",current_item)]],
--      [[string.format("x%02x",current_item)]],
--  },
-- })
sedish("/system/apps/gfx.p64/update.lua",{
    { -- don't flip when you press ctrl-v (noticeable when undoing)
        [[if (keyp("v"))]],
        [[if (keyp"v" and not key"ctrl")]],
    },
})

sedish("/system/lib/gui_ed.lua",{
    { -- fix custom key callbacks in gui
        [[content.key_callback(k)]],
        [[content.key_callback[k](k)]],
    },
})

-- doesn't work for startup terminal
--   need to wait for it to regenerate, e.g. after running a fullscreen app
sedish("/system/apps/terminal.lua",{
    { -- add custom terminal_cd event (to let my z.lua util "run" cd for you)
        [[-- scroll down only if needed]],
        [[on_event("terminal_cd",function(msg) cd(msg.path) end)]],
    },
    { -- show slightly different terminal prompt when in upgraded terminal
        [[return result -- custom prompt goes here]],
        [[return "\f6"..pwd().."\f7 > "]],
    },
})

printh "sedish done"