[CmdletBinding()]
param(
    [Parameter(Mandatory = $true)]
    [ValidateNotNullOrEmpty()]
    [string]$Task,

    [Parameter(Mandatory = $true)]
    [ValidatePattern('^[A-Za-z0-9_-]+$')]
    [string]$Developer,

    [Parameter(Mandatory = $true)]
    [ValidateNotNullOrEmpty()]
    [string[]]$PlannedPath,

    [Parameter(Mandatory = $true)]
    [ValidateNotNullOrEmpty()]
    [string[]]$Contract,

    [string]$Remote = 'origin',
    [string]$BaseRef = 'origin/main'
)

$ErrorActionPreference = 'Stop'

function Invoke-Git {
    param([Parameter(ValueFromRemainingArguments = $true)][string[]]$Arguments)

    $output = & git @Arguments 2>&1

    if ($LASTEXITCODE -ne 0) {
        throw "Git 命令执行失败：git $($Arguments -join ' ')`n$($output -join "`n")"
    }

    return @($output)
}

function Normalize-RepoPath {
    param([string]$Path)

    return ($Path.Trim() -replace '\\', '/').TrimStart('.', '/').TrimEnd('/')
}

function Test-PathOverlap {
    param(
        [string]$Planned,
        [string]$Changed
    )

    return $Planned -eq $Changed `
        -or $Changed.StartsWith($Planned + '/', [StringComparison]::OrdinalIgnoreCase) `
        -or $Planned.StartsWith($Changed + '/', [StringComparison]::OrdinalIgnoreCase)
}

$repoRoot = (Invoke-Git rev-parse --show-toplevel | Select-Object -First 1).Trim()
$repoName = Split-Path -Leaf $repoRoot
$originUrl = (Invoke-Git remote get-url $Remote | Select-Object -First 1).Trim()
$gitUser = (Invoke-Git config user.name | Select-Object -First 1).Trim()

if ($repoName -ne 'CaiWuXiTong') {
    throw "当前目录不是 CaiWuXiTong：$repoRoot"
}

if ($originUrl -notmatch 'WuYongJie/CaiWuXiTong(?:\.git)?$') {
    throw "远程仓库不是 WuYongJie/CaiWuXiTong：$originUrl"
}

if ([string]::IsNullOrWhiteSpace($gitUser)) {
    throw 'Git user.name 未配置。'
}

$plannedPaths = @($PlannedPath | ForEach-Object { Normalize-RepoPath $_ } | Where-Object { $_ } | Select-Object -Unique)
$contracts = @($Contract | ForEach-Object { $_.Trim() } | Where-Object { $_ } | Select-Object -Unique)

if ($plannedPaths.Count -eq 0 -or $contracts.Count -eq 0) {
    throw '必须同时提供预计修改路径和公共契约关键词，不能在范围不明确时开始开发。'
}

Invoke-Git fetch --prune $Remote | Out-Null
Invoke-Git rev-parse --verify $BaseRef | Out-Null

$status = @(Invoke-Git status --porcelain=v1)
$trackedChanges = @($status | Where-Object { $_ -and -not $_.StartsWith('?? ') })
$untrackedChanges = @($status | Where-Object { $_ -and $_.StartsWith('?? ') })

if ($trackedChanges.Count -gt 0) {
    Write-Host '阻断：工作区已有受控文件改动，不能开始新任务。' -ForegroundColor Red
    $trackedChanges | ForEach-Object { Write-Host "  $_" }
    exit 2
}

$currentBranch = (Invoke-Git branch --show-current | Select-Object -First 1).Trim()
$remoteBranches = @(
    Invoke-Git for-each-ref '--format=%(refname:short)' "refs/remotes/$Remote" |
        Where-Object {
            $_ -and
            $_ -ne $Remote -and
            $_ -ne "$Remote/HEAD" -and
            $_ -ne $BaseRef -and
            $_ -ne "$Remote/$currentBranch"
        }
)

$branchFindings = @()

foreach ($branch in $remoteBranches) {
    $counts = ((Invoke-Git rev-list --left-right --count "$BaseRef...$branch") | Select-Object -First 1).Trim() -split '\s+'
    $branchOnly = [int]$counts[1]

    if ($branchOnly -eq 0) {
        continue
    }

    & git merge-base --is-ancestor $branch $BaseRef
    if ($LASTEXITCODE -eq 0) {
        continue
    }

    $changedFiles = @(Invoke-Git diff --name-only "$BaseRef...$branch" | ForEach-Object { Normalize-RepoPath $_ })
    $pathHits = @()

    foreach ($planned in $plannedPaths) {
        foreach ($changed in $changedFiles) {
            if (Test-PathOverlap -Planned $planned -Changed $changed) {
                $pathHits += $changed
            }
        }
    }

    $subject = (Invoke-Git log -1 '--format=%s' $branch | Select-Object -First 1).Trim()
    $diffText = (Invoke-Git diff --unified=0 "$BaseRef...$branch") -join "`n"
    $contractHits = @(
        $contracts | Where-Object {
            $branch -match [Regex]::Escape($_) `
                -or $subject -match [Regex]::Escape($_) `
                -or $diffText -match [Regex]::Escape($_)
        }
    )

    if ($pathHits.Count -gt 0 -or $contractHits.Count -gt 0) {
        $branchFindings += [pscustomobject]@{
            Branch       = $branch
            Subject      = $subject
            PathHits     = @($pathHits | Select-Object -Unique)
            ContractHits = @($contractHits | Select-Object -Unique)
        }
    }
}

$existingFindings = @()
$searchRoots = @('app', 'config', 'database', 'modules', 'resources', 'routes', 'tests')

foreach ($keyword in $contracts) {
    $matches = @(& git grep -n -I -F -e $keyword $BaseRef -- @searchRoots 2>$null)

    if ($LASTEXITCODE -notin @(0, 1)) {
        throw "检查主线公共契约失败：$keyword"
    }

    if ($matches.Count -gt 0) {
        $existingFindings += [pscustomobject]@{
            Keyword = $keyword
            Matches = @($matches | Select-Object -First 8)
        }
    }
}

Write-Host "Codex 任务开工检查：$Task" -ForegroundColor Cyan
Write-Host "开发者：$Developer；Git 身份：$gitUser；基线：$BaseRef"
Write-Host "预计路径：$($plannedPaths -join ', ')"
Write-Host "公共契约：$($contracts -join ', ')"

if ($untrackedChanges.Count -gt 0) {
    Write-Host '提醒：存在未跟踪文件，Codex 必须确认归属且不得顺带提交：' -ForegroundColor Yellow
    $untrackedChanges | ForEach-Object { Write-Host "  $_" }
}

if ($existingFindings.Count -gt 0) {
    Write-Host '主线已存在相同关键词，请先复用或说明差异：' -ForegroundColor Yellow

    foreach ($finding in $existingFindings) {
        Write-Host "  [$($finding.Keyword)]"
        $finding.Matches | ForEach-Object { Write-Host "    $_" }
    }
}

if ($branchFindings.Count -gt 0) {
    Write-Host '阻断：以下远程任务分支与当前计划重叠。停止修改，由相关开发者先完成协调：' -ForegroundColor Red

    foreach ($finding in $branchFindings) {
        Write-Host "  $($finding.Branch) — $($finding.Subject)"

        if ($finding.PathHits.Count -gt 0) {
            Write-Host "    重叠路径：$($finding.PathHits -join ', ')"
        }

        if ($finding.ContractHits.Count -gt 0) {
            Write-Host "    重叠契约：$($finding.ContractHits -join ', ')"
        }
    }

    exit 2
}

Write-Host '通过：未发现远程任务分支与当前计划重叠。可以创建或继续独立任务分支。' -ForegroundColor Green
exit 0