#!/usr/bin/env pwsh
<#
.SYNOPSIS
    Resets the challenge environment to a specific checkpoint.

.DESCRIPTION
    This script allows you to jump to any checkpoint in the module,
    resetting your repository to that state. Useful for skipping ahead,
    starting over, or practicing specific sections.

.PARAMETER Checkpoint
    The checkpoint to reset to: start, merge, or merge-conflict.
    If not specified, displays help information.

.EXAMPLE
    .\reset.ps1
    Shows available checkpoints and current status.

.EXAMPLE
    .\reset.ps1 start
    Resets to the beginning (branching basics section).

.EXAMPLE
    .\reset.ps1 merge
    Jumps to the merging section (feature-login branch already exists).

.EXAMPLE
    .\reset.ps1 merge-conflict
    Jumps to the conflict resolution section (merge already complete).
#>

param(
    [ValidateSet('start', 'merge', 'merge-conflict', '')]
    [string]$Checkpoint = ''
)

# Checkpoint to tag mapping
$checkpointTags = @{
    'start' = 'checkpoint-start'
    'merge' = 'checkpoint-merge'
    'merge-conflict' = 'checkpoint-merge-conflict'
}

# Checkpoint descriptions
$checkpointDescriptions = @{
    'start' = 'Branching Basics - Create and work with feature branches'
    'merge' = 'Merging Branches - Merge feature-login into main'
    'merge-conflict' = 'Resolving Conflicts - Fix merge conflicts in config.json'
}

# ============================================================================
# Display help if no checkpoint specified
# ============================================================================
if ($Checkpoint -eq '') {
    Write-Host "`n=== Module 03: Branching and Merging - Checkpoints ===" -ForegroundColor Cyan
    Write-Host "`nAvailable checkpoints:" -ForegroundColor White
    Write-Host ""

    foreach ($key in @('start', 'merge', 'merge-conflict')) {
        $desc = $checkpointDescriptions[$key]
        Write-Host "  $key" -ForegroundColor Green -NoNewline
        Write-Host " - $desc" -ForegroundColor White
    }

    Write-Host "`nUsage:" -ForegroundColor Cyan
    Write-Host "  .\reset.ps1 <checkpoint>" -ForegroundColor White
    Write-Host ""
    Write-Host "Examples:" -ForegroundColor Cyan
    Write-Host "  .\reset.ps1 start           # Start from the beginning" -ForegroundColor White
    Write-Host "  .\reset.ps1 merge           # Jump to merging section" -ForegroundColor White
    Write-Host "  .\reset.ps1 merge-conflict  # Jump to conflict resolution" -ForegroundColor White
    Write-Host ""

    # Try to detect current checkpoint
    if (Test-Path "challenge/.git") {
        Push-Location "challenge"
        $currentBranch = git branch --show-current 2>$null
        $currentCommit = git rev-parse HEAD 2>$null

        # Check which checkpoint we're at
        $currentCheckpoint = $null
        foreach ($cp in @('start', 'merge', 'merge-conflict')) {
            $tagCommit = git rev-parse $checkpointTags[$cp] 2>$null
            if ($currentCommit -eq $tagCommit) {
                $currentCheckpoint = $cp
                break
            }
        }

        if ($currentCheckpoint) {
            Write-Host "Current checkpoint: " -ForegroundColor Yellow -NoNewline
            Write-Host "$currentCheckpoint" -ForegroundColor Green -NoNewline
            Write-Host " (on branch $currentBranch)" -ForegroundColor Yellow
        } else {
            Write-Host "Current status: " -ForegroundColor Yellow -NoNewline
            Write-Host "In progress (on branch $currentBranch)" -ForegroundColor White
        }

        Pop-Location
    }

    Write-Host ""
    exit 0
}

# ============================================================================
# Validate challenge directory exists
# ============================================================================
if (-not (Test-Path "challenge")) {
    Write-Host "[ERROR] Challenge directory not found." -ForegroundColor Red
    Write-Host "Run .\setup.ps1 first to create the challenge environment." -ForegroundColor Yellow
    exit 1
}

if (-not (Test-Path "challenge/.git")) {
    Write-Host "[ERROR] No git repository found in challenge directory." -ForegroundColor Red
    Write-Host "Run .\setup.ps1 first to create the challenge environment." -ForegroundColor Yellow
    exit 1
}

# Navigate to challenge directory
Push-Location "challenge"

# ============================================================================
# Verify the checkpoint tag exists
# ============================================================================
$targetTag = $checkpointTags[$Checkpoint]
$tagExists = git tag -l $targetTag

if (-not $tagExists) {
    Write-Host "[ERROR] Checkpoint tag '$targetTag' not found." -ForegroundColor Red
    Write-Host "Run ..\setup.ps1 to recreate the challenge environment." -ForegroundColor Yellow
    Pop-Location
    exit 1
}

# ============================================================================
# Check for uncommitted changes
# ============================================================================
$statusOutput = git status --porcelain 2>$null

if ($statusOutput) {
    Write-Host "`n[WARNING] You have uncommitted changes!" -ForegroundColor Yellow
    Write-Host "The following changes will be lost:" -ForegroundColor Yellow
    Write-Host ""
    git status --short
    Write-Host ""

    $response = Read-Host "Continue and discard all changes? (y/N)"
    if ($response -ne 'y' -and $response -ne 'Y') {
        Write-Host "`nReset cancelled." -ForegroundColor Cyan
        Pop-Location
        exit 0
    }
}

# ============================================================================
# Reset to checkpoint
# ============================================================================
Write-Host "`nResetting to checkpoint: $Checkpoint" -ForegroundColor Cyan
Write-Host "Description: $($checkpointDescriptions[$Checkpoint])" -ForegroundColor White
Write-Host ""

try {
    # Reset to the checkpoint tag
    git reset --hard $targetTag 2>&1 | Out-Null

    # Clean untracked files
    git clean -fd 2>&1 | Out-Null

    # Ensure we're on main branch
    $currentBranch = git branch --show-current
    if ($currentBranch -ne 'main') {
        git switch main 2>&1 | Out-Null
        git reset --hard $targetTag 2>&1 | Out-Null
    }

    Write-Host "[SUCCESS] Reset to checkpoint '$Checkpoint' complete!" -ForegroundColor Green
    Write-Host ""

    # Show what to do next
    switch ($Checkpoint) {
        'start' {
            Write-Host "Next steps:" -ForegroundColor Cyan
            Write-Host "  1. Create a new branch: git switch -c feature-login" -ForegroundColor White
            Write-Host "  2. Create login.py and make 2+ commits" -ForegroundColor White
            Write-Host "  3. Verify: ..\verify.ps1 start" -ForegroundColor White
        }
        'merge' {
            Write-Host "Next steps:" -ForegroundColor Cyan
            Write-Host "  1. View branch structure: git log --oneline --graph --all" -ForegroundColor White
            Write-Host "  2. Merge feature-login: git merge feature-login" -ForegroundColor White
            Write-Host "  3. Verify: ..\verify.ps1 merge" -ForegroundColor White
        }
        'merge-conflict' {
            Write-Host "Next steps:" -ForegroundColor Cyan
            Write-Host "  1. Attempt merge: git merge update-config" -ForegroundColor White
            Write-Host "  2. Resolve conflicts in config.json" -ForegroundColor White
            Write-Host "  3. Complete merge: git add config.json && git commit" -ForegroundColor White
            Write-Host "  4. Verify: ..\verify.ps1 merge-conflict" -ForegroundColor White
        }
    }

    Write-Host ""
    Write-Host "View current state: git log --oneline --graph --all" -ForegroundColor Cyan
    Write-Host ""

} catch {
    Write-Host "[ERROR] Failed to reset to checkpoint." -ForegroundColor Red
    Write-Host $_.Exception.Message -ForegroundColor Red
    Pop-Location
    exit 1
}

Pop-Location
exit 0