$ErrorActionPreference = 'Stop'

$ScriptDir = Split-Path -Parent $MyInvocation.MyCommand.Path
$RepoRoot = Split-Path -Parent $ScriptDir
$CanonicalHome = if ($env:COPILOT_RESOURCES_HOME) { $env:COPILOT_RESOURCES_HOME } else { Join-Path $HOME '.copilot-resources' }
$StateDir = if ($env:COPILOT_RESOURCES_STATE_DIR) { $env:COPILOT_RESOURCES_STATE_DIR } else { Join-Path $HOME '.copilot-resources-state' }
$CopilotHome = if ($env:COPILOT_HOME) { $env:COPILOT_HOME } else { Join-Path $HOME '.copilot' }
$VscodeUserDir = if ($env:VSCODE_USER_DIR) { $env:VSCODE_USER_DIR } else { Join-Path $env:APPDATA 'Code\User' }
$ManagedShellEnv = $null
$ProfilePath = $PROFILE.CurrentUserAllHosts
$VscodeSettingsFile = Join-Path $VscodeUserDir 'settings.json'

function Resolve-Directory {
    param([string]$Path)
    (Resolve-Path -LiteralPath $Path).Path
}

function Ensure-Directory {
    param([string]$Path)
    if (-not (Test-Path -LiteralPath $Path)) {
        New-Item -ItemType Directory -Path $Path -Force | Out-Null
    }
}

function Find-NodeExecutable {
    foreach ($Candidate in @('node', 'node.exe', 'nodejs', 'nodejs.exe')) {
        $Command = Get-Command $Candidate -ErrorAction SilentlyContinue | Select-Object -First 1
        if ($Command) {
            return $Command.Source
        }
    }

    return $null
}

function Quote-SingleQuoted {
    param([string]$Value)

    "'" + $Value.Replace("'", "''") + "'"
}

function Ensure-Junction {
    param(
        [string]$Target,
        [string]$Path
    )

    $Parent = Split-Path -Parent $Path
    Ensure-Directory $Parent

    if (Test-Path -LiteralPath $Path) {
        $Existing = Get-Item -LiteralPath $Path -Force
        if ($Existing.LinkType -eq 'Junction' -or $Existing.LinkType -eq 'SymbolicLink') {
            $ResolvedTarget = Resolve-Directory $Existing.Target
            if ($ResolvedTarget -eq (Resolve-Directory $Target)) {
                return
            }
        }

        if ($Existing.PSIsContainer -and -not (Get-ChildItem -LiteralPath $Path -Force | Select-Object -First 1)) {
            Remove-Item -LiteralPath $Path -Force
        } else {
            throw "Refusing to replace existing path: $Path"
        }
    }

    New-Item -ItemType Junction -Path $Path -Target $Target | Out-Null
}

function Upsert-ManagedBlock {
    param(
        [string]$Path,
        [string]$BeginMarker,
        [string]$EndMarker,
        [string]$Body
    )

    Ensure-Directory (Split-Path -Parent $Path)
    $Lines = if (Test-Path -LiteralPath $Path) { Get-Content -LiteralPath $Path } else { @() }
    $Output = New-Object System.Collections.Generic.List[string]
    $Skip = $false

    foreach ($Line in $Lines) {
        if ($Line -eq $BeginMarker) {
            $Skip = $true
            continue
        }

        if ($Line -eq $EndMarker) {
            $Skip = $false
            continue
        }

        if (-not $Skip) {
            $Output.Add($Line)
        }
    }

    if ($Output.Count -gt 0) {
        $Output.Add('')
    }

    $Output.Add($BeginMarker)
    foreach ($BodyLine in ($Body -split "`r?`n")) {
        $Output.Add($BodyLine)
    }
    $Output.Add($EndMarker)

    Set-Content -LiteralPath $Path -Value $Output
}

function Write-ManagedPowerShellEnv {
    $script:ManagedShellEnv = Join-Path $StateDir 'copilot-cli-env.ps1'
    Ensure-Directory (Split-Path -Parent $script:ManagedShellEnv)

    @(
        '$env:COPILOT_RESOURCES_HOME = ' + (Quote-SingleQuoted $CanonicalHome),
        '$env:COPILOT_HOME = ' + (Quote-SingleQuoted $CopilotHome),
        '$env:COPILOT_CUSTOM_INSTRUCTIONS_DIRS = ' + (Quote-SingleQuoted (Join-Path $CanonicalHome 'resources\instructions'))
    ) | Set-Content -LiteralPath $script:ManagedShellEnv

    $QuotedEnvPath = Quote-SingleQuoted $script:ManagedShellEnv
    Upsert-ManagedBlock \
        -Path $ProfilePath \
        -BeginMarker '# >>> copilot-resources bootstrap >>>' \
        -EndMarker '# <<< copilot-resources bootstrap <<<' \
        -Body "if (Test-Path -LiteralPath $QuotedEnvPath) {`n    . $QuotedEnvPath`n}"
}

function Merge-VscodeSettings {
    $NodeExecutable = Find-NodeExecutable
    if (-not $NodeExecutable) {
        Write-Warning 'Skipping VS Code settings merge because Node.js is not available.'
        return
    }

    Ensure-Directory (Split-Path -Parent $VscodeSettingsFile)
    & $NodeExecutable (Join-Path $ScriptDir 'merge-vscode-settings.mjs') --target $VscodeSettingsFile --template (Join-Path $CanonicalHome 'config\vscode\settings.template.jsonc') --set "COPILOT_RESOURCES_HOME=$CanonicalHome"
}

Ensure-Directory (Split-Path -Parent $CanonicalHome)
if (Test-Path -LiteralPath $CanonicalHome) {
    if ((Resolve-Directory $CanonicalHome) -ne (Resolve-Directory $RepoRoot)) {
        throw "Canonical path already exists and points elsewhere: $CanonicalHome"
    }
} else {
    New-Item -ItemType Junction -Path $CanonicalHome -Target $RepoRoot | Out-Null
}

Ensure-Directory $CopilotHome
Ensure-Directory $VscodeUserDir

Ensure-Junction -Target (Join-Path $CanonicalHome 'resources\skills') -Path (Join-Path $CopilotHome 'skills')
Ensure-Junction -Target (Join-Path $CanonicalHome 'resources\agents') -Path (Join-Path $CopilotHome 'agents')
Ensure-Junction -Target (Join-Path $CanonicalHome 'resources\instructions') -Path (Join-Path $CopilotHome 'instructions')
Ensure-Junction -Target (Join-Path $CanonicalHome 'resources\hooks') -Path (Join-Path $CopilotHome 'hooks')
Ensure-Junction -Target (Join-Path $CanonicalHome 'resources\prompts') -Path (Join-Path $VscodeUserDir 'prompts')

Write-ManagedPowerShellEnv
Merge-VscodeSettings

Ensure-Directory $StateDir
@{
    canonicalHome = $CanonicalHome
    repoRoot = $RepoRoot
    copilotHome = $CopilotHome
    vscodeUserDir = $VscodeUserDir
    vscodeSettingsFile = $VscodeSettingsFile
    shellRcFile = $ProfilePath
    managedShellEnv = $ManagedShellEnv
    bootstrapScript = (Join-Path $ScriptDir 'bootstrap.ps1')
} | ConvertTo-Json | Set-Content -LiteralPath (Join-Path $StateDir 'install-state.json')

Write-Host "Bootstrap complete."
Write-Host "Canonical home: $CanonicalHome"
Write-Host "Repository root: $RepoRoot"
Write-Host "Copilot home: $CopilotHome"
Write-Host "VS Code user dir: $VscodeUserDir"
Write-Host "Merged managed VS Code settings into: $VscodeSettingsFile"
Write-Host "Installed managed Copilot CLI PowerShell environment into: $ManagedShellEnv"
Write-Host "Linked PowerShell profile: $ProfilePath"
Write-Host "Optional VS Code template: $(Join-Path $CanonicalHome 'config\vscode\settings.template.jsonc')"