import * as fs from 'fs'

import * as core from '@actions/core'

const DEFAULT_INSTRUCTIONS_PATH = '.github/release-notes-instructions.md'

export interface ActionInputs {

baseRef: string

headRef: string

instructionsPath: string | undefined

model: string | undefined

prStrategy: 'merge-commits' | 'github-api'

}

export function getInputs(): ActionInputs {

const baseRef = core.getInput('base-ref', {required: true})

if (!baseRef) {

throw new Error('base-ref is required')

}

const headRef = core.getInput('head-ref') || 'HEAD'

const instructionsPath = resolveInstructionsPath(

core.getInput('instructions') || undefined

)

const model = core.getInput('model') || undefined

const prStrategyRaw = core.getInput('pr-strategy') || 'merge-commits'

if (prStrategyRaw !== 'merge-commits' && prStrategyRaw !== 'github-api') {

throw new Error(

`Invalid pr-strategy: ${prStrategyRaw}. Must be 'merge-commits' or 'github-api'`

)

}

return {

baseRef,

headRef,

instructionsPath,

model,

prStrategy: prStrategyRaw

}

}

/**

* Resolve the instructions file path:

* 1. If explicitly provided via input, use that

* 2. Otherwise, check for .github/release-notes-instructions.md in the workspace

* 3. If neither exists, return undefined (generic mode)

*/

function resolveInstructionsPath(

explicit: string | undefined

): string | undefined {

if (explicit) {

core.info(`📖 Using explicit instructions: ${explicit}`)

return explicit

}

if (fs.existsSync(DEFAULT_INSTRUCTIONS_PATH)) {

core.info(

`📖 Auto-discovered instructions: ${DEFAULT_INSTRUCTIONS_PATH}`

)

return DEFAULT_INSTRUCTIONS_PATH

}

core.info('📖 No custom instructions found — using generic mode')

return undefined

}