package queue

import (
	"fmt"
	"sync"
	"time"
)

// ErrAlreadyQueued is returned when a job with the same commit was recently queued
var ErrAlreadyQueued = fmt.Errorf("job already queued with this commit")

// CommitDedup tracks recently queued commits to prevent duplicate submissions
type CommitDedup struct {
	mu      sync.RWMutex
	commits map[string]time.Time // key: "job_name:commit_id" -> queued_at
	ttl     time.Duration
}

// NewCommitDedup creates a new commit deduplication tracker
func NewCommitDedup(ttl time.Duration) *CommitDedup {
	if ttl <= 0 {
		ttl = 1 * time.Hour // Default 1 hour TTL
	}
	return &CommitDedup{
		commits: make(map[string]time.Time),
		ttl:     ttl,
	}
}

// IsDuplicate checks if a job+commit combination was recently queued
func (d *CommitDedup) IsDuplicate(jobName, commitID string) bool {
	key := d.key(jobName, commitID)

	d.mu.RLock()
	defer d.mu.RUnlock()

	if t, ok := d.commits[key]; ok {
		if time.Since(t) < d.ttl {
			return true // Still within TTL, consider duplicate
		}
	}
	return false
}

// MarkQueued records that a job+commit combination was just queued
func (d *CommitDedup) MarkQueued(jobName, commitID string) {
	key := d.key(jobName, commitID)

	d.mu.Lock()
	defer d.mu.Unlock()

	d.commits[key] = time.Now()
}

// Cleanup removes expired entries (call periodically, e.g., every 5 minutes)
func (d *CommitDedup) Cleanup() {
	d.mu.Lock()
	defer d.mu.Unlock()

	now := time.Now()
	for id, t := range d.commits {
		if now.Sub(t) > d.ttl {
			delete(d.commits, id)
		}
	}
}

// key generates a unique key for job+commit combination
func (d *CommitDedup) key(jobName, commitID string) string {
	return jobName + ":" + commitID
}

// Size returns the number of tracked commits (for metrics/debugging)
func (d *CommitDedup) Size() int {
	d.mu.RLock()
	defer d.mu.RUnlock()
	return len(d.commits)
}