# build.ps1 - build a Power C program for the C64 on a fresh work disk, then
# optionally leave it back in BASIC, loaded and running.
#
#   powershell -NoProfile -File build.ps1
#   powershell -NoProfile -File build.ps1 -Run -Keys 'vim.c\njjj'
#   powershell -NoProfile -File build.ps1 -Shell 'l\n'          (poke at the disk)
#
# Everything happens in ONE emulator session: compile each unit, link, then
# "bye" out of the Power C shell, load the program from BASIC and run it. One
# session is not just faster, it is required: two emulators both attached to
# work.d81 write the image back over each other on exit and the files made by
# the other one disappear.
#
# Power C is interactive - cc asks which disk to insert three times, the linker
# wants one object file per ">" line, "^" for the libraries, an empty RETURN
# and then a name - so every prompt is answered from the -keybuf string. VICE
# paces those keystrokes in wall-clock milliseconds while the machine runs at
# warp, so the delay has to be long enough that a step's answers arrive after
# its prompt: cc, for one, clears the keyboard buffer when it starts.

param(
    [string]$Prog = "vim",
    [string]$Keys = "",
    [string]$Shell = "",
    [int]$Delay = 900,           # ms per keystroke; wall clock, machine is at warp
    [int]$Pad = 20,              # spare RETURNs while a step is working
    [int]$Tail = 8,              # spare RETURNs while the linker writes
    [int]$Settle = 0,            # extra seconds to run after the last key (screen redraw)
    [switch]$Full,               # ignore the stamps: fresh disk, recompile everything
    [switch]$Run
)

$ErrorActionPreference = "Stop"

$vice  = "C:\Program Files\GTK3VICE-3.10-win64\bin"
$x64   = Join-Path $vice "x64sc.exe"
$c1541 = Join-Path $vice "c1541.exe"
$here  = $PSScriptRoot
$base  = Join-Path $here "..\reference\POWERc.d81"
$shots = Join-Path $here "shots"

# VICE splits "image:file" on a colon, so keep the image name bare and run from
# this folder.
Set-Location $here
$img = "work.d81"

$units = @{
    vim = @("vim", "vscreen", "vview", "vedit", "vdir", "vml")
    mltest = @("mltest", "vml")
}
if (-not $units.ContainsKey($Prog)) { throw "unknown program '$Prog'" }
$unitList = $units[$Prog]

if (-not (Test-Path $x64))  { throw "x64sc.exe not found in $vice" }
if (-not (Test-Path $base)) { throw "$base not found - is the repository complete?" }
New-Item -ItemType Directory -Force -Path $shots | Out-Null

# ---------------------------------------------------------------- petscii

# Power C sources live on the disk as PETSCII SEQ files with CR line endings:
# a-z -> $41-$5A, A-Z -> $C1-$DA, CRLF -> CR, and the four characters the manual
# says are typed with shift/logo keys: { | } ~ -> $DB $DC $DD $DE.
function ConvertTo-Petscii([string]$in, [string]$out) {
    $bytes = [IO.File]::ReadAllBytes($in)
    $start = 0
    if ($bytes.Length -ge 3 -and $bytes[0] -eq 0xEF -and
        $bytes[1] -eq 0xBB -and $bytes[2] -eq 0xBF) { $start = 3 }
    $o = New-Object System.Collections.Generic.List[byte]
    for ($i = $start; $i -lt $bytes.Length; $i++) {
        $b = $bytes[$i]
        if ($b -eq 13) { continue }
        if ($b -eq 10) { $o.Add([byte]13); continue }
        if ($b -ge 0x61 -and $b -le 0x7A) { $o.Add([byte]($b - 0x20)); continue }
        if ($b -ge 0x41 -and $b -le 0x5A) { $o.Add([byte]($b + 0x80)); continue }
        if ($b -ge 0x7B -and $b -le 0x7F) { $o.Add([byte]($b + 0x60)); continue }
        $o.Add([byte]$b)
    }
    [IO.File]::WriteAllBytes($out, $o.ToArray())
    return $o.Count
}

# ---------------------------------------------------------------- emulator

# Quote one argument the way the Windows command line wants it. Start-Process's
# -ArgumentList joins with spaces and does not quote anything, which silently
# split "-keybuf cc vim.c\n" into two arguments, so the command line is built
# here and handed to .NET as a single string.
function Quote-Arg([string]$a) {
    if ($a -ne "" -and $a -notmatch '[\s"]') { return $a }
    $e = $a -replace '(\\*)"', '$1$1\"'
    $e = $e -replace '(\\+)$', '$1$1'
    return '"' + $e + '"'
}

# Exactly one emulator, waited for, so nothing else touches the image.
function Invoke-C64 {
    param(
        [string]$KeyBuf,
        [string]$Shot,
        [string]$Target = "shell",
        [int]$Cycles = 0,
        [int]$KeyDelay = 900
    )
    if (Test-Path $Shot) { Remove-Item $Shot -Force }   # VICE won't overwrite
    if ($Cycles -le 0) {
        $wall = ($KeyBuf.Length * $KeyDelay / 1000.0) + 15 + $Settle
        $c = [long]($wall * 13000000)
        if ($c -lt 150000000) { $c = 150000000 }
        if ($c -gt 2000000000) { $c = 2000000000 }
        $Cycles = [int]$c
    }
    $argv = @(
        "-8", $img,
        "-autostart", ($img + ":" + $Target),
        "-autostart-warp", "-warp", "-sounddev", "dummy",
        "-keybuf-delay", "$KeyDelay",
        "-keybuf", $KeyBuf,
        "-limitcycles", "$Cycles",
        "-exitscreenshot", $Shot
    )
    $cmdline = ($argv | ForEach-Object { Quote-Arg $_ }) -join ' '
    $psi = New-Object System.Diagnostics.ProcessStartInfo
    $psi.FileName = $x64
    $psi.Arguments = $cmdline
    $psi.UseShellExecute = $false
    $pi = [System.Diagnostics.Process]::Start($psi)
    $pi.WaitForExit()
    Start-Sleep -Milliseconds 900        # let the image write settle
}

function Get-DiskDir {
    return (& $c1541 $img -list 2>$null) -join "`n"
}

# ---------------------------------------------------------------- raw shell

if ($Shell -ne "") {
    if (-not (Test-Path $img)) { throw "$img not found - build something first" }
    Invoke-C64 -KeyBuf $Shell -Shot (Join-Path $shots "shell.png") -KeyDelay $Delay
    Write-Host "shots\shell.png"
    exit 0
}

# ---------------------------------------------------------------- fresh disk

# work.stamp remembers the hash of each .c as it was last compiled onto the work
# disk. Only units whose hash differs are converted, copied over and recompiled;
# the others keep the .o already on the disk. The linker then runs again.
$stampFile = Join-Path $here "work.stamp"
$stamps = @{}
if (Test-Path $stampFile) {
    foreach ($ln in (Get-Content $stampFile)) {
        $p = $ln -split '='
        if ($p.Count -eq 2) { $stamps[$p[0]] = $p[1] }
    }
}
if ($Full -or -not (Test-Path $img) -or -not (Test-Path $stampFile)) {
    Write-Host "== fresh work disk"
    Copy-Item $base $img -Force
    $stamps = @{}
} else {
    Write-Host "== incremental build on $img"
}

$changed = @()
foreach ($u in $unitList) {
    $src = Join-Path $here "$u.c"
    if (-not (Test-Path $src)) { throw "$src not found" }
    $hash = (Get-FileHash $src -Algorithm MD5).Hash
    if ($stamps[$u] -eq $hash) { continue }
    $changed += $u
    $pet = Join-Path $here "$u.pet"
    $n = ConvertTo-Petscii $src $pet
    Write-Host ("== {0}.c changed -> petscii ({1} bytes)" -f $u, $n)
    # cc and the linker refuse to overwrite, so scratch the stale copies first
    $null = & $c1541 $img -delete "$u.c" "$u.o" 2>$null
    $null = & $c1541 $img -write $pet "$u.c,s" 2>$null
    $stamps.Remove($u)               # only re-stamped once its .o really exists
}
$haveProg = ((& $c1541 $img -list 2>$null) -join "`n") -match ('"' + [regex]::Escape($Prog) + '"\s+prg')
$needLink = ($changed.Count -gt 0) -or (-not $haveProg)
if ($needLink -and $haveProg) { $null = & $c1541 $img -delete $Prog 2>$null }
if ($changed.Count -eq 0) { Write-Host "== no source changed" }

# ---------------------------------------------------------------- one session

# cc <unit> and RETURNs for its disk prompts, over and over, then the linker:
# ">" object files, ">" up-arrow for the libraries, ">" empty to finish, the
# output name. With -Run the session goes on to leave the shell with bye, load
# the program from BASIC and type -Keys at whatever it puts on the screen.
$kb = ""
foreach ($u in $changed) {
    $kb += "cc $u.c\n" + ("\n" * 3) + ("\n" * $Pad)
}
if ($needLink) {
    $kb += "link -s\n"
    foreach ($u in $unitList) { $kb += "$u.o\n" }
    $kb += "^\n\n" + $Prog + "\n" + ("\n" * $Tail)
}
if ((-not $Run) -and ($kb -eq "")) {
    Write-Host "build ok - nothing to do"
    exit 0
}
if ($Run) {
    $kb += "bye\n" + ("\n" * 6)             # let the shell hand back to BASIC
    $kb += 'load"' + $Prog + '",8,1' + "\n" + ("\n" * 10)   # let the load finish
    $kb += "run\n"
    $kb += $Keys
}

$shot = if ($Run) { Join-Path $shots "run.png" } else { Join-Path $shots "build.png" }
Write-Host ("== one session: cc [{0}], {1}{2}" -f ($changed -join ' '),
    $(if ($needLink) { 'link' } else { 'no link' }),
    $(if ($Run) { ', bye, load, run' } else { '' }))
Invoke-C64 -KeyBuf $kb -Shot $shot -KeyDelay $Delay

$dir = Get-DiskDir
$found = $false
foreach ($line in ($dir -split "`n")) {
    if ($line -match ('"' + [regex]::Escape($Prog) + '"\s+prg')) { $found = $true }
    if ($line -match ('"(' + ($unitList -join '|') + ')\.[co]"')) {
        Write-Host "   $line"
    }
}

# stamp a unit only once its object file is really on the disk
foreach ($u in $changed) {
    if ($dir -match ('"' + [regex]::Escape($u) + '\.o"')) {
        $stamps[$u] = (Get-FileHash (Join-Path $here "$u.c") -Algorithm MD5).Hash
    } else {
        Write-Host "   $u.c produced no object - read $shot"
    }
}
($stamps.GetEnumerator() | ForEach-Object { "{0}={1}" -f $_.Key, $_.Value }) | Set-Content $stampFile
if (-not $found) { throw "'$Prog' was not created - read $shot" }

if ($Run) {
    Write-Host ("   {0}" -f (Split-Path $shot -Leaf))
} else {
    Write-Host "build ok - 'build.ps1 -Run -Keys ...' to try it"
}