//
//  ContextSelectionServiceTests.swift
//  oAITests
//
// SPDX-License-Identifier: PolyForm-Noncommercial-1.0.0
// Copyright (C) 2026 Rune Olsen

import Testing
@testable import oAI

@Suite("ContextSelectionService pure scoring helpers")
struct ContextSelectionServiceTests {

    private var service: ContextSelectionService { ContextSelectionService.shared }

    // MARK: - getImportanceScore

    @Test("A short message with no cost or token data scores from length alone")
    func lowScoreForPlainShortMessage() {
        let message = Message(role: .user, content: "hi")
        #expect(service.getImportanceScore(message) < 0.01)
    }

    @Test("Cost, length, and token factors combine to the exact weighted sum")
    func combinesWeightedFactors() {
        // cost 0.005 / 0.01 = 0.5 -> * 0.5 weight = 0.25
        // 1000 chars / 2000 = 0.5 -> * 0.3 weight = 0.15
        // 500 tokens / 1000 = 0.5 -> * 0.2 weight = 0.1
        // total = 0.5
        let message = Message(role: .assistant, content: String(repeating: "a", count: 1000), tokens: 500, cost: 0.005)
        #expect(abs(service.getImportanceScore(message) - 0.5) < 0.0001)
    }

    @Test("Score is capped at 1.0 even when every factor maxes out and would otherwise overflow it")
    func scoreIsCappedAtOne() {
        let message = Message(
            role: .assistant,
            content: String(repeating: "a", count: 5000), // well past the 2000-char max
            tokens: 5000, // well past the 1000-token max
            cost: 1.0 // well past the $0.01 max
        )
        #expect(service.getImportanceScore(message) == 1.0)
    }

    // MARK: - estimateTokens

    @Test("Uses the message's actual token count when present")
    func usesActualTokenCountWhenAvailable() {
        let messages = [Message(role: .user, content: "irrelevant for this test", tokens: 42)]
        #expect(service.estimateTokens(messages) == 42)
    }

    @Test("Falls back to content.count / 4 when tokens is nil")
    func fallsBackToCharacterEstimate() {
        let messages = [Message(role: .user, content: String(repeating: "x", count: 40))]
        #expect(service.estimateTokens(messages) == 10)
    }

    @Test("Sums estimates across a mix of messages with and without token counts")
    func sumsAcrossMixedMessages() {
        let messages = [
            Message(role: .user, content: "ignored", tokens: 100),
            Message(role: .assistant, content: String(repeating: "y", count: 20)), // 20/4 = 5
        ]
        #expect(service.estimateTokens(messages) == 105)
    }
}