param(
    [Parameter(Mandatory = $true)]
    [string]$LibraryRoot,
    [string]$TargetRoot = (Get-Location).Path,
    [string]$Query = "",
    [string]$Type = "",
    [string]$Domain = "",
    [int]$Top = 10,
    [switch]$Json,
    [switch]$Rebuild
)

$ErrorActionPreference = "Stop"

if (-not (Test-Path -LiteralPath $LibraryRoot)) {
    throw "Library root does not exist: $LibraryRoot"
}

if (-not (Test-Path -LiteralPath $TargetRoot)) {
    throw "Target root does not exist: $TargetRoot"
}

$libraryPath = (Resolve-Path -LiteralPath $LibraryRoot).Path
$targetPath = (Resolve-Path -LiteralPath $TargetRoot).Path
$scriptDir = Split-Path -Parent $MyInvocation.MyCommand.Path
$detectScript = Join-Path $scriptDir "detect-project-signals.ps1"
$indexPath = Join-Path $libraryPath "_indexes\artifacts-index.json"
$buildScript = Join-Path $libraryPath "scripts\build-artifact-index.ps1"

if (-not (Test-Path -LiteralPath $detectScript)) {
    throw "Missing detect-project-signals script: $detectScript"
}

if ($Rebuild -or -not (Test-Path -LiteralPath $indexPath)) {
    if (-not (Test-Path -LiteralPath $buildScript)) {
        throw "Library artifact index is missing and no build script was found: $indexPath"
    }

    & $buildScript -Root $libraryPath -OutputPath $indexPath -Quiet
}

if (-not (Test-Path -LiteralPath $indexPath)) {
    throw "Library artifact index does not exist: $indexPath"
}

$signalInfo = & $detectScript -Root $targetPath -Json | ConvertFrom-Json
$signalNames = @()
if ($null -ne $signalInfo -and $null -ne $signalInfo.signals) {
    $signalNames = @($signalInfo.signals | ForEach-Object { $_.name } | Where-Object { -not [string]::IsNullOrWhiteSpace($_) })
}

$signalsValue = $signalNames -join ","

if ($signalNames.Count -eq 0 -and
    [string]::IsNullOrWhiteSpace($Query) -and
    [string]::IsNullOrWhiteSpace($Type) -and
    [string]::IsNullOrWhiteSpace($Domain)) {
    throw "No target project signals or search criteria were found. Provide -Query, -Type, or -Domain."
}

function Get-Terms {
    param([string]$Value)

    $terms = New-Object System.Collections.Generic.List[string]
    foreach ($part in [regex]::Split($Value.ToLowerInvariant(), "[\s,;\uFF0C\uFF1B\u3001]+")) {
        $trimmed = $part.Trim()
        if (-not [string]::IsNullOrWhiteSpace($trimmed)) {
            [void]$terms.Add($trimmed)
        }
    }

    return @($terms)
}

function Get-TextValue {
    param($Value)

    if ($null -eq $Value) {
        return ""
    }

    if ($Value -is [array]) {
        return (@($Value) -join " ")
    }

    return [string]$Value
}

function Test-ContainsText {
    param(
        [string]$Haystack,
        [string]$Needle
    )

    if ([string]::IsNullOrWhiteSpace($Haystack) -or [string]::IsNullOrWhiteSpace($Needle)) {
        return $false
    }

    return $Haystack.ToLowerInvariant().Contains($Needle.ToLowerInvariant())
}

function Test-ExactText {
    param(
        [string[]]$Values,
        [string]$Needle
    )

    foreach ($value in @($Values)) {
        if (-not [string]::IsNullOrWhiteSpace($value) -and $value.Trim().ToLowerInvariant() -eq $Needle.Trim().ToLowerInvariant()) {
            return $true
        }
    }

    return $false
}

function Add-Score {
    param(
        [int]$Current,
        [string]$FieldValue,
        [string]$Term,
        [int]$Weight,
        [string]$FieldName,
        [System.Collections.Generic.List[string]]$MatchedFields
    )

    if (Test-ContainsText -Haystack $FieldValue -Needle $Term) {
        [void]$MatchedFields.Add($FieldName)
        return ($Current + $Weight)
    }

    return $Current
}

$terms = @(Get-Terms -Value $Query)
$rawItems = Get-Content -Raw -Encoding UTF8 -LiteralPath $indexPath | ConvertFrom-Json
$items = @()
if ($null -ne $rawItems) {
    if ($rawItems -is [array]) {
        $items = @($rawItems)
    }
    else {
        $items = @($rawItems)
    }
}

$rankableResults = New-Object System.Collections.Generic.List[object]

foreach ($item in $items) {
    if (-not [string]::IsNullOrWhiteSpace($Type) -and ((Get-TextValue $item.type).ToLowerInvariant() -ne $Type.ToLowerInvariant())) {
        continue
    }

    if (-not [string]::IsNullOrWhiteSpace($Domain) -and ((Get-TextValue $item.domain).ToLowerInvariant() -ne $Domain.ToLowerInvariant())) {
        continue
    }

    $score = 0
    $matchedTerms = New-Object System.Collections.Generic.HashSet[string]
    $matchedSignals = New-Object System.Collections.Generic.List[string]
    $matchedFields = New-Object System.Collections.Generic.List[string]

    foreach ($signal in $signalNames) {
        if (Test-ExactText -Values @($item.appliesWhen) -Needle $signal) {
            [void]$matchedSignals.Add($signal)
            $score += 70
        }
    }

    foreach ($term in $terms) {
        $termScore = 0
        $termScore = Add-Score -Current $termScore -FieldValue (Get-TextValue $item.title) -Term $term -Weight 80 -FieldName "title" -MatchedFields $matchedFields
        $termScore = Add-Score -Current $termScore -FieldValue (Get-TextValue $item.tags) -Term $term -Weight 60 -FieldName "tags" -MatchedFields $matchedFields
        $termScore = Add-Score -Current $termScore -FieldValue (Get-TextValue $item.domain) -Term $term -Weight 35 -FieldName "domain" -MatchedFields $matchedFields
        $termScore = Add-Score -Current $termScore -FieldValue (Get-TextValue $item.category) -Term $term -Weight 25 -FieldName "category" -MatchedFields $matchedFields
        $termScore = Add-Score -Current $termScore -FieldValue (Get-TextValue $item.appliesWhen) -Term $term -Weight 35 -FieldName "appliesWhen" -MatchedFields $matchedFields
        $termScore = Add-Score -Current $termScore -FieldValue (Get-TextValue $item.targetOutputs) -Term $term -Weight 25 -FieldName "targetOutputs" -MatchedFields $matchedFields
        $termScore = Add-Score -Current $termScore -FieldValue (Get-TextValue $item.body) -Term $term -Weight 15 -FieldName "body" -MatchedFields $matchedFields

        if ($termScore -gt 0) {
            [void]$matchedTerms.Add($term)
            $score += $termScore
        }
    }

    if ($terms.Count -gt 0 -and $matchedTerms.Count -eq $terms.Count) {
        $score += 30
    }

    if ($signalNames.Count -gt 0 -and $matchedSignals.Count -eq $signalNames.Count) {
        $score += 25
    }

    if ($score -gt 0 -or ($terms.Count -eq 0 -and $signalNames.Count -eq 0)) {
        [void]$rankableResults.Add([pscustomobject]@{
            score = $score
            type = $item.type
            title = $item.title
            domain = $item.domain
            category = $item.category
            relativePath = $item.relativePath
            fullPath = $item.fullPath
            tags = @($item.tags)
            appliesWhen = @($item.appliesWhen)
            targetOutputs = @($item.targetOutputs)
            updated = $item.updated
            matchedTerms = @($matchedTerms)
            matchedSignals = @($matchedSignals | Select-Object -Unique)
            matchedFields = @($matchedFields | Select-Object -Unique)
        })
    }
}

$results = @($rankableResults.ToArray() |
    Sort-Object `
        @{ Expression = "score"; Descending = $true },
        @{ Expression = "updated"; Descending = $true },
        @{ Expression = "relativePath"; Descending = $false } |
    Select-Object -First $Top)

$selection = [pscustomobject]@{
    libraryRoot = $libraryPath
    targetRoot = $targetPath
    signals = @($signalInfo.signals)
    indexPath = $indexPath
    query = $Query
    type = $Type
    domain = $Domain
    results = @($results)
}

if ($Json) {
    ConvertTo-Json -InputObject $selection -Depth 10
    return
}

Write-Host "Library: $libraryPath"
Write-Host "Target: $targetPath"
if ($signalNames.Count -gt 0) {
    Write-Host "Signals: $($signalNames -join ', ')"
}
else {
    Write-Host "Signals: none"
}

if ($results.Count -eq 0) {
    Write-Host "No matching library assets selected."
    return
}

foreach ($result in $results) {
    Write-Host "[$($result.score)] $($result.type): $($result.title)"
    Write-Host "  path: $($result.relativePath)"
    if (@($result.targetOutputs).Count -gt 0) {
        Write-Host "  targetOutputs: $(@($result.targetOutputs) -join ', ')"
    }
}