package rp

import (
	"fmt"
	"strings"

	"github.com/blang/semver/v4"
	"github.com/leodido/go-conventionalcommits"
)

type Releases struct {
	Latest *Tag
	Stable *Tag
}

type VersioningStrategy = func(Releases, conventionalcommits.VersionBump, NextVersionType) (string, error)

var _ VersioningStrategy = SemVerNextVersion

func SemVerNextVersion(r Releases, versionBump conventionalcommits.VersionBump, nextVersionType NextVersionType) (string, error) {
	latest, err := parseSemverWithDefault(r.Latest)
	if err != nil {
		return "", fmt.Errorf("failed to parse latest version: %w", err)
	}

	stable, err := parseSemverWithDefault(r.Stable)
	if err != nil {
		return "", fmt.Errorf("failed to parse stable version: %w", err)
	}

	// If there is a previous stable release, we use that as the version anchor. Falling back to any pre-releases
	// if they are the only tags in the repo.
	next := latest
	if r.Stable != nil {
		next = stable
	}

	switch versionBump {
	case conventionalcommits.UnknownVersion:
		return "", fmt.Errorf("invalid latest bump (unknown)")
	case conventionalcommits.PatchVersion:
		err = next.IncrementPatch()
	case conventionalcommits.MinorVersion:
		err = next.IncrementMinor()
	case conventionalcommits.MajorVersion:
		err = next.IncrementMajor()
	}
	if err != nil {
		return "", err
	}

	switch nextVersionType {
	case NextVersionTypeUndefined, NextVersionTypeNormal:
		next.Pre = make([]semver.PRVersion, 0)
	case NextVersionTypeAlpha, NextVersionTypeBeta, NextVersionTypeRC:
		id := uint64(0)

		if len(latest.Pre) >= 2 && latest.Pre[0].String() == nextVersionType.String() {
			if latest.Pre[1].String() == "" || !latest.Pre[1].IsNumeric() {
				return "", fmt.Errorf("invalid format of previous tag")
			}
			id = latest.Pre[1].VersionNum + 1
		}

		setPRVersion(&next, nextVersionType.String(), id)
	}

	return "v" + next.String(), nil
}

func VersionBumpFromCommits(commits []AnalyzedCommit) conventionalcommits.VersionBump {
	bump := conventionalcommits.UnknownVersion

	for _, commit := range commits {
		entryBump := conventionalcommits.UnknownVersion
		switch {
		case commit.BreakingChange:
			entryBump = conventionalcommits.MajorVersion
		case commit.Type == "feat":
			entryBump = conventionalcommits.MinorVersion
		case commit.Type == "fix":
			entryBump = conventionalcommits.PatchVersion
		}

		if entryBump > bump {
			bump = entryBump
		}
	}

	return bump
}

func setPRVersion(version *semver.Version, prType string, count uint64) {
	version.Pre = []semver.PRVersion{
		{VersionStr: prType},
		{VersionNum: count, IsNum: true},
	}
}

func parseSemverWithDefault(tag *Tag) (semver.Version, error) {
	version := "v0.0.0"
	if tag != nil {
		version = tag.Name
	}

	// The lib can not handle v prefixes
	version = strings.TrimPrefix(version, "v")

	parsedVersion, err := semver.Parse(version)
	if err != nil {
		return semver.Version{}, fmt.Errorf("failed to parse version %q: %w", version, err)
	}

	return parsedVersion, nil
}