# Compare branches to detect unmerged commits (e.g. prod hotfix not merged to main)
# Usage: local repo path OR Gitea owner/repo
# -CompareSet full: main vs uat, main vs prod, uat vs prod

param(
    [string]$RepoPath,
    [string]$Owner,
    [string]$Repo,
    [string]$BaseBranch = "main",
    [string]$HeadBranch = "prod",
    [ValidateSet("single", "full")]
    [string]$CompareSet = "single",
    [string]$SinceTag,
    [string]$SinceDate,
    [string]$ApiToken = $env:GITEA_TOKEN,
    [string]$GiteaBaseUrl = "http://afe.git:3000"
)

$ErrorActionPreference = "Stop"
$ConfigPath = Join-Path (Split-Path -Parent $MyInvocation.MyCommand.Path) "..\config.local.json"
if (-not $ApiToken -and (Test-Path $ConfigPath)) {
    $cfg = Get-Content $ConfigPath -Raw | ConvertFrom-Json
    $ApiToken = $cfg.ApiToken
    if ($cfg.GiteaBaseUrl) { $GiteaBaseUrl = $cfg.GiteaBaseUrl }
}

function Get-GitLog {
    param([string]$Path, [string]$Range, [string]$Since)
    $gitArgs = @("log", $Range, "--no-merges", "--format=%h | %an | %s")
    if ($Since) { $gitArgs += "--since=$Since" }
    $out = & git -C $Path $gitArgs 2>&1
    if ($out) { $out } else { @() }
}

function Compare-Local {
    if (-not (Test-Path (Join-Path $RepoPath ".git"))) {
        Write-Host "Error: Not a git repo: $RepoPath"; exit 1
    }
    cmd /c "git -C `"$RepoPath`" fetch origin >nul 2>&1"
    $since = if ($SinceDate) { $SinceDate } else { $null }
    $baseRef = "origin/$BaseBranch"
    $headRef = "origin/$HeadBranch"
    if ($SinceTag -and -not $SinceDate) {
        $tagDate = & git -C $RepoPath log -1 --format="%ci" $SinceTag 2>$null
        if ($tagDate) { $since = $tagDate.Trim().Split(" ")[0] }
    }
    Write-Host "=== Branch Compare: ${BaseBranch} vs ${HeadBranch} ===" -ForegroundColor Cyan
    Write-Host "Repo: $RepoPath" -ForegroundColor Gray
    Write-Host ""
    $inHeadNotBase = @(Get-GitLog -Path $RepoPath -Range "${baseRef}..${headRef}" -Since $since)
    $inBaseNotHead = @(Get-GitLog -Path $RepoPath -Range "${headRef}..${baseRef}" -Since $since)
    Write-Host "[!] Commits in ${HeadBranch} NOT in ${BaseBranch} (need merge to ${BaseBranch}):" -ForegroundColor Yellow
    if ($inHeadNotBase.Count -eq 0) {
        Write-Host "    (none)" -ForegroundColor Green
    } else {
        $inHeadNotBase | ForEach-Object { Write-Host "    $_" }
        Write-Host "    Total: $($inHeadNotBase.Count) commits" -ForegroundColor Yellow
    }
    Write-Host ""
    Write-Host "[i] Commits in ${BaseBranch} NOT in ${HeadBranch} (${BaseBranch} is ahead):" -ForegroundColor Gray
    if ($inBaseNotHead.Count -eq 0) {
        Write-Host "    (none)" -ForegroundColor Gray
    } else {
        $inBaseNotHead | ForEach-Object { Write-Host "    $_" }
        Write-Host "    Total: $($inBaseNotHead.Count) commits" -ForegroundColor Gray
    }
    if ($inHeadNotBase.Count -gt 0) {
        $byUser = $inHeadNotBase | ForEach-Object {
            $parts = $_ -split '\s*\|\s*'
            if ($parts.Count -ge 2) { $parts[1].Trim() }
        } | Where-Object { $_ } | Group-Object | Sort-Object Count -Descending
        Write-Host ""
        Write-Host "By user (unmerged):" -ForegroundColor Yellow
        $byUser | ForEach-Object { Write-Host "    $($_.Name): $($_.Count) commits" }
        Write-Host ""
        Write-Host "ACTION: Merge ${HeadBranch} into ${BaseBranch} to sync hotfixes." -ForegroundColor Red
    }
}

function Compare-API {
    if (-not $ApiToken) { Write-Host "Error: ApiToken required for API mode"; exit 1 }
    if (-not $Owner -or -not $Repo) { Write-Host "Error: Owner and Repo required for API mode"; exit 1 }
    $ApiBase = "$GiteaBaseUrl/api/v1"
    $Headers = @{ "Authorization" = "token $ApiToken"; "Content-Type" = "application/json" }
    $basehead = "${BaseBranch}...${HeadBranch}"
    Write-Host "=== Branch Compare: ${BaseBranch} vs ${HeadBranch} ===" -ForegroundColor Cyan
    Write-Host "Repo: $Owner/$Repo (via API)" -ForegroundColor Gray
    Write-Host ""
    try {
        $cmp = Invoke-RestMethod -Uri "$ApiBase/repos/$Owner/$Repo/compare/$basehead" -Headers $Headers -Method Get
        $commits = if ($cmp.commits) { @($cmp.commits) } else { @() }
        Write-Host "[!] Commits in ${HeadBranch} NOT in ${BaseBranch} (need merge to ${BaseBranch}):" -ForegroundColor Yellow
        if ($commits.Count -eq 0) {
            Write-Host "    (none)" -ForegroundColor Green
        } else {
            $commits | ForEach-Object {
                $author = $_.commit.author.name
                if ($_.author.login) { $author = $_.author.login }
                Write-Host "    $($_.sha.Substring(0,7)) | $author | $($_.commit.message.Split("`n")[0])"
            }
            Write-Host "    Total: $($commits.Count) commits" -ForegroundColor Yellow
        }
        Write-Host ""
        $baseheadRev = "${HeadBranch}...${BaseBranch}"
        $cmpRev = Invoke-RestMethod -Uri "$ApiBase/repos/$Owner/$Repo/compare/$baseheadRev" -Headers $Headers -Method Get
        $commitsRev = if ($cmpRev.commits) { @($cmpRev.commits) } else { @() }
        Write-Host "[i] Commits in ${BaseBranch} NOT in ${HeadBranch} (${BaseBranch} is ahead):" -ForegroundColor Gray
        if ($commitsRev.Count -eq 0) {
            Write-Host "    (none)" -ForegroundColor Gray
        } else {
            $commitsRev | ForEach-Object {
                $author = $_.commit.author.name
                if ($_.author.login) { $author = $_.author.login }
                Write-Host "    $($_.sha.Substring(0,7)) | $author | $($_.commit.message.Split("`n")[0])"
            }
            Write-Host "    Total: $($commitsRev.Count) commits" -ForegroundColor Gray
        }
        if ($commits.Count -gt 0) {
            $byUser = $commits | ForEach-Object {
                if ($_.author.login) { $_.author.login } else { $_.commit.author.name }
            } | Group-Object | Sort-Object Count -Descending
            Write-Host ""
            Write-Host "By user (unmerged):" -ForegroundColor Yellow
            $byUser | ForEach-Object { Write-Host "    $($_.Name): $($_.Count) commits" }
            Write-Host ""
            Write-Host "ACTION: Merge ${HeadBranch} into ${BaseBranch} to sync hotfixes." -ForegroundColor Red
        }
    } catch {
        $msg = if ($_.ErrorDetails.Message) { $_.ErrorDetails.Message } else { $_.Exception.Message }
        if ($msg -match "BaseNotExist|HeadNotExist|not found") {
            Write-Host "  (branch not found - repo may not have ${BaseBranch}/${HeadBranch})" -ForegroundColor Gray
        } else {
            Write-Host "  API Error: $msg" -ForegroundColor Red
        }
    }
}

$pairs = @()
if ($CompareSet -eq "full") {
    $pairs = @(
        @{ Base = "main"; Head = "uat" },
        @{ Base = "main"; Head = "prod" },
        @{ Base = "uat"; Head = "prod" }
    )
} else {
    $pairs = @(@{ Base = $BaseBranch; Head = $HeadBranch })
}

foreach ($p in $pairs) {
    $BaseBranch = $p.Base
    $HeadBranch = $p.Head
    if ($RepoPath) {
        Compare-Local
    } elseif ($Owner -and $Repo) {
        Compare-API
    } else {
        Write-Host "Error: Provide -RepoPath (local) OR -Owner and -Repo (API)"
        Write-Host "  Local:  .\branch_compare.ps1 -RepoPath 'd:\path\to\repo' -CompareSet full"
        Write-Host "  API:    .\branch_compare.ps1 -Owner G3SF -Repo g3fo-trade -CompareSet full"
        exit 1
    }
    if ($pairs.Count -gt 1) { Write-Host "" }
}