Improve cross-platform development setup (solver path handling + dependency conflict)

[parthdagia05]

Description: Improve Cross-Platform Development Setup (macOS/Linux)

Closes #10

Summary

This PR addresses two primary blockers for running MUIO from source on non-Windows platforms (specifically macOS/Apple Silicon and Linux). It refactors solver path resolution to move away from hard-coded Windows-centric paths and fixes a dependency conflict that prevented clean environment builds.

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Changes

1. Dynamic Solver Path Handling

Refactored OsemosysClass.py and Config.py to move away from hard-coded, platform-specific directory strings.

Resolution Priority Logic:

1. Environment Variables: Checks for MUIO_GLPK_PATH or MUIO_CBC_PATH (useful for custom CI/CD or container setups).
2. Windows Defaults: Preserves existing behavior using SOLVERs_FOLDER if on Windows.
3. System Discovery: On macOS/Linux, it now uses shutil.which() to find glpsol or cbc in the user's $PATH (e.g., Homebrew or APT installs).

Technical Impact:

• No import-time crashes if solvers are missing.
• Runtime RuntimeError provides clear feedback if a solver is called but not found.
• Full support for Apple Silicon via system-installed binaries.

2. Dependency Resolution Fix

Fixed a ResolutionImpossible error during pip install -r requirements.txt.

• Conflict: botocore required urllib3 < 1.27, but requirements.txt pinned urllib3==2.2.1.
• Fix: Downgraded pin to urllib3==1.26.18. This satisfies all current project dependencies and allows for clean virtual environment creation.

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Manual Verification (macOS Apple Silicon)

Tests conducted on macOS 14.x (M1 Pro) in a fresh Python 3.9 environment.

1. Installation: pip install -r requirements.txt now completes without errors.
2. Discovery: * Installed glpk and cbc via Homebrew.
   • Verified Config.GLPK_PATH and Config.CBC_PATH correctly resolve to /opt/homebrew/bin and /opt/homebrew/opt/cbc/bin respectively.
3. End-to-End: * Successfully launched the app via python API/app.py.
   • Triggered model execution from the UI; solvers executed correctly via the new path resolution logic.
   • Verified output results were generated without permission or path errors.

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Backward Compatibility

• Windows: The logic specifically preserves the existing Path(SOLVERs_FOLDER, ...) structure. Windows users and existing .exe build workflows are unaffected.
• Logic: No changes were made to the actual solver execution arguments, only the directory resolution.

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✅ Checklist

• Code follows the style guidelines of this project.
• I have performed a self-review of my own code.
• My changes generate no new warnings.
• Dependency versions have been tested for compatibility.
• Documentation/comments updated where necessary.

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[SeaCelo]

@parthdagia05 Take a look at Muio-Mac as well. I think moving the path issue to upstream is a good idea

[parthdagia05]

@SeaCelo
Thank you for the suggestion.

I will review the Muio-Mac repository to understand how solver paths are currently handled there and assess whether the path resolution logic should be unified across both codebases.

If appropriate, I can propose aligning the implementation so that solver discovery is handled consistently upstream rather than only within this branch.

I’ll follow up shortly after reviewing Muio-Mac.

[parthdagia05]

@SeaCelo

I reviewed the MUIO-Mac repository. It installs GLPK and CBC via Homebrew and relies on them being available on the system PATH.The current upstream refactor uses shutil.which() for solver discovery on macOS/Linux, which should make upstream MUIO compatible with the same Homebrew-based setup without requiring hard-coded paths.

If appropriate, I would be happy to align further with the MUIO-Mac approach to ensure consistency between repositories and avoid duplicated platform-specific logic.

Please let me know if you'd prefer adjustments to better integrate with the macOS port.

[SeaCelo]

@parthdagia05 I don't maintain this repo so I can't speak for how it should be handled here. MUIO-Mac is fully downstream, but any upstream changes that makes the porting easier are well appreciated.

[parthdagia05]

@SeaCelo okay i get it !