REBOL [
    Title: "To Do Script"
    File-name: %to-do-guru.r
    Date: 10-June-2008
    Author: "Ed O'Connor"
    License: "MIT"
]

cmds: [
    ['add     | 'create ]  set str string!                  (add-task str)        |
    ['replace | 'swap   ]  set id integer! set str string!  (replace-task id str) |
    ['append  | 'affix  ]  set id integer! set str string!  (append-task id str)  |
    ['pri     | 'rank   ]  set id integer! set str string!  (prioritize)          |
    ['done    | 'do     ]  set id integer!                  (mark-complete id)    |
    ['find    | 'search ]  set str string!                  (find-tasks str)      |
    ['listpri | 'lspri  ]                                   (print-tasks/pri)     |
    ['listhab | 'lshab  ]                                   (print-tasks/hab)     |
    ['list    | 'ls     ]                                   (print-tasks)         |
    ['help    | '?      ]                                   (print "help tbd")    |
    ['editor  | 'gui    ]                                   (launch-editor)       |
    ['archive | 'arch   ]                                   (archive)             |
    ['restore | 'rs     ]                                   (restore)             | 
    ['quit    | 'q      ]  (print "Session ended." halt)
]

read-tasks: func [/local id][
    tasks: any [attempt [read/lines %todo.txt] copy []]
    id: 0 
    forskip tasks 2 [
        id: id + 1 
        insert tasks id
    ]
    sort/skip/compare tasks 2 2
]

save-tasks: func [/local task-write output out][
    task-write: copy tasks
    sort/skip task-write 2
    output: extract/index task-write 2 2
    out: make string! 100
    foreach item output [repend out [item newline]]
    write %todo.txt out
]

add-task: func [task [string!]][
    either not empty? trim task [
        next-id: add 1 (length? tasks) / 2
        repend tasks [next-id task]
        save-tasks
    ][
        print "Error: Missing task description."
    ]
]

append-task: func [index [integer!] fragm [string!] /local task][
    either find tasks index [
        task: select tasks index
        append task rejoin [" " fragm]
        save-tasks
    ][
        print "Task number not found."
    ]
]

replace-task: func [index [integer!] newstr [string!] /local task][
    either find tasks index [
        task: select tasks index
        task: newstr
        save-tasks
    ][
        print "Task number not found."
    ]
]

mark-complete: func [index [integer!] /local task][
    either > length? tasks 0 [
        task: select tasks index
        insert task "X "
        save-tasks
    ][
        print "Task number does not exist."
    ]
]

archive: does [
    either > length? tasks 0 [
        foreach [i t] tasks [
            if #"X" = first t [write/append %done.txt rejoin [t newline]]           
        ]
        remove-each [i t] tasks [#"X" = first t]
        save-tasks
        read-tasks
    ][
        print "No tasks currently marked for archiving."
    ]
]

restore: does [
    done: any [attempt [read/lines %done.txt] copy []]
    either all [
        > length? done 0 
        exists %todo.txt
    ][
        foreach task done [
            unless #"X" = first t [write/append %todo.txt rejoin [task newline]]           
        ]
        remove-each [i t] done [#"X" <> first task]
        write/lines %done.txt done
        save-tasks
        read-tasks
    ][
        print "Unable to restore tasks: Missing todo.txt and/or done.txt."
    ]
]

alpha: charset [#"A" - #"Z" #"a" - #"z"]
pri-format: ["(" some alpha ")"]

print-tasks: func [/pri /hab /local output] [
    output: copy []
    print "CURRENT TASKS"
    foreach [i t] tasks [
        if pri [parse/all t [some [pri-format (repend output [i t]) break | skip]]]
        if hab [parse/all t [any ["~recur"   (repend output [i t]) break | skip]]]
        unless any [pri hab][repend output [i t]]
    ]
    foreach [i t] output [print rejoin [i ": " t]]
    print [(length? output) / 2 "tasks listed." newline]
]

find-tasks: func [params [string!] /local criteria ][
    criteria: parse/all params " "
    rule: copy [skip]    
    foreach param criteria [
        insert rule [(print rejoin [i ": " t]) break |] 
        insert rule compose [(param)]  
    ]
    foreach [i t] tasks [bind rule 'i parse/all t [some rule]]
]

launch-editor: does [
    either system/product = 'view [
        editor %todo.txt
    ][
        print "Sorry, REBOL/View is required to launch the GUI editor".
    ]
]

read-tasks

forever [   
    unless parse load/all ask "to-do >> " [cmds] [print "? Input not recognized."]
]